I don't know that anyone can answer the question about loving what you do vs. physical pain. It really isn't a bipolar question. Reading your post, it does seem as if you're a bit hypomanic, though. The best thing to do would be to get a psych evaluation. There are a lot of disorders that could cause you to be self-destructive if your focus on your work is an obsession. Then again, you could just be a really passionate person with lots of energy!

The "who am I?" question is one I think people over complicate. At least I do. I've decided that Popeye had the best answer to that question..."I am what I am." Hope that helps.