Hey hun, first off well done for wanting to turn your life around your incredibly brave so well done!
So your going to get a chi how exciting !! Have you thought about of you want a long coat or short coat yet ?
My sister had a similar issue a long time ago, I was very young but I remember that fizzy drinks really helped her. I also remember that her putting on weight took time and the right attitude, like you have. You have overcome the first steps and what better incentive than becoming a mummy to a chi !!
I'm seeing my sister today (who is now 30 and had the eating disorder at 17) I will ask her for you how she over come it. It's still something she doesn't like to talk about but I'm sure she can give some tips to help you out. I will pm you with what she says.
You seem like a great person and I know your chi when you get him/ her will love you lots and lots. If you ever need a chat or just someone to listen im here for you as sometimes its easier to talk to people you don't know. Also if you find a breeder or a chi you really like I can help you do some checks and see of they are healthy etc via online.
You heading in the right direction so well done.