First, do not make any wedding plans. Instead, make a full time job out of finding a job. You will never be independent unless you can earn your own money. Go out and work. There you can find friends with whom you may be able to rent a room from. Even if you need government assistance, do it to get some mental health help. Some medication can do wonders for your life, so I suggest you seriously do what you have to do in order to get mental health help.
Unless you are in an abusive relationship, stay put so you can get your life together and still have a roof over your head. Again, do not make any wedding plans as marriage is not the answer to your problems. You cannot possibly love someone and be in a healthy relationship unless you first love yourself.
Nothing is ever going to change unless YOU make some changes. Your fiancé works, so perhaps at least he can help you get on medication to stabilize your mental health issues. While you are waiting for that to happen, find a job, any job. No doors are ever going to open for you unless you begin taking steps to improve your lifestyle.