Have you seen your surgeon recently? Did anyone tell you any exercises, and are you doing any exercises at home? Can you bend and straighten your leg? If you are 4 months post op, and are still using crutches, then you either have something going on with your knee, or you have had inadequate rehab. If you do not have any insurance, is there anyway you could possibly pay for one or two sessions to be shown what you need to be doing?
I know that I have just asked a lot of questions, but it is hard to give appropriate advice unless we know a few more details.
It sounds like you have a very busy life and need to get back to some sort of normal function!
Sorry you are having such a rough time!