I wish I could answer for you but I can really empathize! I've never kept a job longer than 6 months either, besides my current one where I've been for 14 months. In the past two weeks I've gotten two write ups though, and my mood and personality have been brought up more frequently. Being constantly fired or fearing a swift axe around every corner makes it even more difficult to function in a work environment. It sounds like we share the hopelessness of feeling like no place will take us, no matter our willingness to work
I hope someone else can help you.