I personally think your problems are within, and don't really have anything to do with your family. You stated that you take 'hormone tablets' and will fly off the handle at people for saying things to you. I get the feeling that this is not only for people online, you are probably very snappy at home. And for someone who sometimes seems very smart and mature, you can be extremely childish.
If you'd like to get a job, wait for a few weeks until the university students go back, and you'll find much better openings.
Or, if you must move out, you could get a job with training, like accountancy or care work.
Life is hard Molly I'm afraid, and there is no two ways around it. You must stop feeling like life owes you a better deal, as there will be always someone worse off than you. And in a few years time, you will look back and think 'what on earth was I thinking/doing?'
As for your dad, I look at cars and houses to buy, almost everyday. I have no money, my husband has to pay to go back to university, and I've got to somehow afford to rent a flat along with be a full-time university student. Doesn't mean that I'm going to stop wishing everyday that I could have a beautiful house and a brand new car.
If we did not have these kinds of wishes, then we would have nothing to work for, or any kind of drive.