I've never been exactly in your position, but my experience may serve you in one way or another.
Due to personal and financial circumstances I had to work from a very young age. When I was about 23 I had the chance to go to university to further my education, and so I got my first "real" job at about 27 when I graduated. It was tangentially related to the career I studied (computer science), and it the salary was really low for my degree and my age, but it allowed me to become financially independent and to start improving my quality of life.
After a year or so I it seemed I was stagnant at that job, so I started knocking on doors, but due to my lack of experience (specially at my age) no one wanted to hire me. I don't think my family and friends noticed, but at the time I felt like I was totally worthless. If I was barely able to support myself, how would I have the chance to start a family, to buy a house, or to buy my first car, all things that show the world that you are successful?
But I never stopped knocking on new doors, and eventually I landed a junior position at a local software development company. The salary was more decent, but the most important thing is that I finally had a chance to grow professionally. And fortunately, just one year after I was found out by a large company who wanted to hire me precisely because of the skills I acquired in just that year.
While sometimes it might seem that the world is coming down on you, you need to take a look at the good things in your life to thank for, and do something about the things that could improve or need to change. The first thing I'd do is find a way to get out of that house. This will go in hand with another objective you should set for yourself: find a way to support yourself. Put that degree to work, even if it seems hard or you get turned down at the beginning. Also know that changing careers is totally valid. The most important thing is that you are aware that you are young, you have options open to you, and there is a lot that of growth and improvement yet to come in your life.