I agree with PDM about the counseling. It probably isn't what you want to hear. When we have anxiety and stress, resolution of problems can't come too fast. Somehow, having someone to love and have that relationship to turn to grounds us and becomes the one place in our lives where we can turn for happiness. Unfortunately, if things are still unsettled in other parts of our lives, it taints the love life with stress over bills and financial problems. It sounds like you have been bouncing from one stressful situation to another for a long time. It must be next to impossible to devote enough concentration on the stability of your occupation and the other problems long enough to find direction and solve them. I think, until you are happy in that realm that you will keep bringing baggage to the relationship.
You were the first to recognize the toll it was taking. The two of you cleared the air and separated long enough to decompress and when you did you got along better.
You were doing great until you gave her an ultimatum. I don't believe it was sincere either. It sounds like you wanted her to boost your ego and give you what you really wanted which was "a committment". It backfired on you because it was emotional blackmail. The only time that works is when things have been going well and you don't have a history of stress and turmoil
You have said that she is emotionally unstable and very high matenance. I realize that you feel that she is the "one and only girl for you" but it could also be that you are obsessing a little on her and the relationship because of the stress you have been under.
It would be far better to give yourself time and space to decompress so that you can see the relationship in perpective.
You are trying to get your life together, that should come before you try to share it with someone else.
In any case, honesty, truth, sincereity and consistancy are the cornerstone of any good friendship and romance. You have to have both to be successful. Good luck