My son is a very picky eater who is 24 months and he stayed 25 lbs for at least six months but doc said he was healthy just give him what he wants, my son has a small menu to choose from also and sometimes he will refuse those. I was naturally worried but I had to have faith that he would eventually start eating. Sometimes I would have to fix two and three diff meals at each meal time until I found something he liked. Very fustrating.
It will make sense to wean her off the breast feeding now, as this may actually be interfering with her interest in eating. The symptoms you describe may well be allergy-related, and removing the dog was sensible. If she is well medically, apart from the eating problem, Mother Nature will solve the problem as long as you're introducing appropriate foods.
My daughter was also diagnosed with failure to thrive at 3-4 months. It was also discouraging to me when she would not eat a lot and I too became frustrated. My daughter had other health issues and had a low birth weight. My daughter is 6 now, is very active, eats great, but still on the small side. She was diagnosed with a syndrome called Russell Silver. I do not believe this is a widely known syndrome. I have taken her to a genetisis and a endocrinologist also to be evaluated. Maybe you could contact one of those professionals to get an opinion.