TIFU by trying to get into the wrong car

Some needed backstory for context, ima college student who has my own apartment in this basically college only urbinaztion. Due to certain circumstances my somewhat older uncles fell ill recently and luckily they live in the same urbanization, being approximately an 8 minute walk away from my apartment. Unfortunately my uncle got hospitalized a couple of days ago by being hardheaded and my aunt, following her husbands example, refused to listen to the doctors orders and needed to be hospitalized yesterday. There doing better atm but thats not the main issue, you see both of them lived with one of my uncles mom, my 89yr old grandmother. I stayed with my grandmother all day yesterday after my aunt was hospitalized, but one my cousins, thinking and understanding that college starts tomorrow and ive still got preparations to do, she insisted to take our grandmother with her to her place so I can go back to my apartment and finish my things up and so that my grandmother, who gasnt lived alone for several years now, doesnt stay the night alone. As anybody thats tried to move an elderly person from one place to another for an indefinite ammount of time can tell you, this is not exactly the easiest thing to do. After some back and forth of solid conversation and coersion attempts we settled on the plan that my grandmother would go with my cousin to her house for the night, but will come back the next day since my cousin has to pass by the house to go to her job anyway and either I or one of my neighbors that are basically family would stay with grandma until my cousin left work and picked her up again and this would continue on until either my uncle or aunt would be better enough to leave the hospital and continue on their regular days at their house.

Today was the first day our "keep grandma with someone at all times" plan was going to happen. As usual I wake up do my regular morning routine and after finishing up I texted my cousin to check how things are and if everything ons schedule... but she didnt answer. Knowing how both my grandmother and my cousin can be i figured she was rushing things and umable to answer a text, so I decided to give her a call instead... but no asnwer yet again. This meant one of 2 things, either she was talking with someone from her work or her kid was being distracted with the phone from all the rushing chaos that I imagined the first day of her new morning routines would be, so I wait... and wait... until its about time they should be getting near... so not having much choice, I start walking over to the house so I can take spend my day with my grandmother before I have to start taking shifts with one of the neighbors after starting college tomorrow. As im getting over there I noticed what at the time I beleived to be my cousins van parked and running infront of the house... but if you remember this is basically an urbinaztion where almost all the houses are actually hostels for college students... under normal circumstances the only people that are in that spot are either one of my cousins or me when I bring some stuff in my own car, the neighbors are either hostel owners or college students that both respect everyones parking space and we havent ever really had any issues in that regard. Getting cloaser to the house I notice the gate is actually locked and who I beleived to be my cousin inside of her van talking to somebody who I assumed to be her work through the vans bluetooth speaker (the kind thats stupidly loud). Knowing I dont have a key I callout to my grandmother to her my cousin locked the gate, but the issue is my grandmother is always in one of two places of the house at all times: shes either in her room on the very back of the house where she will never hear me, or shes in the family room watching tv and enjoying the breeze thanks to the some bug shutters and part of the gate which are the only things separating the family room from the outside world. Seeing as she wasnt in the family room, I thought she was in her room.

Not wanting to interrupt who I beleived to be my cousin, who is still at this time in the van and talking to someone who I presumed was her work, I waved at her and pointed at the locked gate, while making a key gesture. At this point, its a good time to say my cousins van has this thing where if the sun hits the windows in a certain way, from the outside you outright cant see anything above a persons chests so at this point, even though im a couple of feet away from the van, I dont actually see the face of the person in the drivers seat, I only see a female outline wearing a uniform and speaking on the phone while also moving her hands around (a completely normal way to have phone conversations down here in puerto rico). So I continue waiting next to the car... then I hear the audible click of the locks when you lock and unlock a car from the inside and her moving her hands towards the passenger seat, the one seat thats infront of me... Meanwhile I was still unaware that this is infact not my cousin having a seemingly very important conversation about her work. I assume this was her way of saying, "grab the keys, I cant give them to you right now" so I did what anybody would do... I tried to open the door... but as I put my hand in the handle and pulled it... it was locked, and thats when I see her face... I have no idea who this girl aas and she has no idea who I am...

The problem is, my dumb ass brain didnt catch up with what my eyes were looking at and for a good 2 seconds with my hand still at the handle, I look at this girl the same way you stare at your computer when its loading. After what seemed like an eternity I immediately backed away from the car, confirm my surroundings and call my cousin... WHO DOESNT ANSWER. So I ended up calling cousin2, the sister of the cousin who has grandma (henceforth dubbed as grandma cousin). And thats when she tells me, grandma cousin didnt have work today so it was unlikely that grandma was going to go back to my aunts house today and that she'll let me know if anything changes but she was as suprised as me that grandma cousin didnt tell me... Immediately I thank her and hang up after telling her to tell my uncles I said hi, and proceed to turn around and face the van which is STILL THERE next to me with the bluetooth speaker phone call and the shocked college newbie who was apparently moving in because, as mentioned before, I know all the neighbors around there and I dont know who this chick was. Keep in mind, im a fairly big guy coming in at 6ft and 200something pounds, there is no way this looks good to me.

I proceeded to awkwardly wave, and say at the top of my lungs, "Sorry, I confused you with someone else" while turning around and speedwalking my way back to my apartment without even waiting or noticing if she had any reaction... AND im still waiting for grandma cousin to call or answer my texts...

TLDR: Family issues lead me to accidentally scare a freshman(presumably) girl by trying to get into her car as a 6ft tall bearded buff guy.