hi feelinglonely
i can certainly identify with a lonely life, but i am one who is ok with it. i am not much of a people person. but i am much older. like u i have attempted to make plans with friends and they just seem to busy. they all have families they have to get home to and just dont seem to have time for me so i have given up. it seems that you have genuinely put an effort forth in to establishing relationships so that you can get out to do things, so it is odd that nothing is panning out. Maybe something is getting lost in the communication somewhere?
As stubborn as you say you are, maybe it would be a good idea to see a therapist for a bit. Just to sort things out. Set some goals. It doesnt sound like you would need intensive therapy. But a therapist could help you with your communication skills to make relationships more successful, help you view life in a different way.
Anyway, welcome to PC. You will find lots of support here. Make sure to check out the chat rooms.