Reading your story I immediately saw two things...
...You have a lot of responsibility for your family, and,
...You are doing wonderfully in 'rising to the occasion'. Very few people in this world could do as well.
All of your 'problems' socially, with your friends, come from them not knowing what your responsibilities are like...ALL of your friends and all of your responsibilities.
I want to cheer at your good sense and thoughtfulness...and at your dreams. Imagine knowing some of what you want to do already...at age 19!!!
And, your inner longings to be free come, simply, from the fact that you can't yet see how this weighty burden will lift.
It will, Babe...it will.
And, NO...you are NOT depressed! 'Depressed' would be that you would hide out in your room and don't do a darn thing for anyone else.
Please don't let anyone give you anti-depressants! You are one healthy girl! I would be proud to call you 'daughter'. Heck, I AM proud of you! That's a fine post you wrote.
Now, as for how to fix the real problem...
...You need a team on the job. You need six more of YOU...each doing one sixth of your tasks, with you supervising and doing only the parts that are your specialties...calming and loving, and growing your own life.
It would be nice to hire these folks, if there is enough money...but then you'd have to accept their 'standards', their ideas on what constitutes appropriate care, particularly in the areas of 'health' and 'tenderness'. That could lead to even greater worries than you have now.
The same might be true if you were to rely on volunteers from your relatives, or any organization.
Everyone might mean well, but they wouldn't necessarily have your practical insight.
Off the top of my head, you might begin with a family meeting...including only you, your parents, and your brother.
I take it that your parents appreciate your help, right? (Your good sense and loving nature must have come from somewhere!)
Could you put it to your immediate family that your own life and future needs attention? And that you have no intention of giving over their welfare and well-being to folks who wouldn't do at least as good a job as you?
Then, you could all brainstorm what services you all need, and who could possibly supply them.
There is a wonderful formula for getting ideas...one that makes everyone present happy they took part. Here's how it goes...
State a wish, and an obstacle, before other people...
Take an idea from the gathered group...
The Wisher then...
...Thanks the Idea-giver, and,
...Says one part of the idea that they like. (There is always something to like in every idea, even the silly ones, and in the ones that aren't for you, just now.)
This is the part that makes everyone glad they spoke up...the thanking, by name...and acknowledging the worth of the idea given, by saying something good about it, aloud.
Meanwhile, someone is writing down the ideas given, so none will be forgotten, later.
I've seen this method done, with large crowds, by the gal that invented it...it is magic, nothing less.
MARYANNE (the Wisher), "My name is Maryanne and I wish to sing and dance and entertain people. My obstacle is that I don't know how to sing and dance."
JAY (an Idea-giver), "My name is Jay and my idea is to go down to such-and-such square, on a Sunday, where the local clowns go to practice, and people come to watch."
MARYANNE, "Thank you, Jay. What I like about your idea is that I would be able to participate, spontaneously, or simply watch. I could develop my own ways, when I am ready."
FLEDGLING (an Idea-giver), "My name is Fledgling and I suggest you could go to a hospital staff cafeteria, at lunch-time, and give an impromptu five-minute song and dance, and maybe a joke."
MARYANNE, "Thank you, Fledgling. What I like about your idea is that hospital workers often need a bit of distraction...to refresh themselves."
Nothing need be committed to right there and then, but participants get out their brilliant ideas, and Maryanne gets ideas she hasn't thought of before, from caring strangers. There is nothing like support!
This comes from Barbara Sher, whose first best-seller has never been promoted, and is free, on-line, at http://www.wishcraft.com
An idea for you, dear 77348...
...Interview the best naturopaths and kinesiologists in town, and ask for them and/or their wisest clients to come to a party like this at your house...(once your family agrees). You supply chairs, and plates for goodies...and ask everyone to bring snacks, if they can.
Then stand up and say your Wish and Obstacle...such as, "I wish for my family's well-being, and my obstacle is time to begin my own life."