Hi
I haven't got time to read the whole thread but I wanted to let you know I was in a similar situation. When I got pg with my daughter in 2009 I was severely bulimic and anorexic, not as bad as you but my BMI was around 16.
For the first few weeks I did find it difficult to come to terms with, but then I realised it is actually an either/or. You either prioritise your baby (and your own bodily needs during pregnancy/breastfeeding) or you prioritise your fears about fat and food. They are not compatible.
The responses saying "oh I was back in my size 6 jeans after a week" or "breastfeeding makes the weight fall off" are not helpful, because what you need to make it work is a complete shift of perspective. I know you were upset by someone upthread sayiing you're not prioritising your baby, because of course you want the best for the baby, but the truth is that you WILL get fat, your body will be out of your control, and it will never be quite the same again, even if you get back to the same weight/size. You have to accept these truths in order to have a happy, successful pregnancy.
Personally having my daughter was the best thing that ever happened to me in terms of sorting out my problems with food. After years of being bulimic/compulsive eating/intermittently starving myself, I found that pregnancy and breastfeeding finally gave me peace with my body. I'm not saying I don't get a bit pissed off with my post-pregnancy body (well, I'm now on my second pregnancy, 19 weeks) but it's like, having produced and fed my beautiful daughter , I finally don't hate my body any more. I lost the baby weight healthily and gradually, but not back down to my pre-pregnancy weight - back to a BMI of about 22.
Also, I hope this comes across in the way it's meant, but it does mean you focus on something else - eating disorders are incredibly inward-looking and obsessive, and it means you are focused on something more impmortant than your own weight/size. and for the first time my partner can actually enjoy meals WITH me, without me disappearing to the loo ten times a day, so he is very happy too 