I know exactly what you're going through; I've been purging/starving for a very long time now, though it's gotten a lot better these past few years, ironically enough because I've really started to enjoy cooking (which still makes me feel horrible). I'm still light, but when I was at my worst a few years ago, I actually passed for female better than I do now-my waist/hip ratio was so much more feminine, I'm sometimes tempted to relapse myself, if only to get my weight down just a little bit. I don't know if I could, and that thought scares me even more.
The key with something like this is to rationalize-you know it will do more harm than good in the long term, and there are better ways of treating dysphoria than starving yourself. If you really feel this dysphoric, you might even want to consider taking a low dose of T-it sounds like you're in a lot of pain, and it's worth exploring anything that could help. HRT helped me immensely-now at least weight isn't going to all of the "male" places, even though I've put on about fifteen since starting-it's scary for me, but I guess I'll live. I wish you the best on your journey-and don't relapse. You know better, I think we all do. We have too.