I've been catching up on this thread. I hope cupcake is doing ok. You seem to be doing great with what you're doing for her and all the research you have done. I can't wait to hear news, I really hope it is good news.
I had a chi when I was about 10 that we got from a horrible breeder. I only realise now, looking back, what a horrible breeder she was. She was very small, probably no more than about 4lbs. After having her for a little while we realised she was pregnant. Obviously my mum knew nothing about breeding and I don't know if she got any advice from the vet or not but all we had was a box with blankets in that was in my bedroom (where she slept). Reading all the information on this site since I got her has realised how stupid and ignorant we were. She ended up giving birth to all 6 of her pups without any problems, but I assume that she could not hold them for long enough due to the amount and her size and despite attempts to keep them warm and feed them they all died. It was an awful experience which still upsets me, but the reason I'm sharing this is because she was small, had no help and was able to deliver naturally. The only problem was delivering too early which doesn't seem to be a problem with cupcake so hopefully all will go well. I will be thinking of you and your sweet little girl (who is beautiful by the way) and sending good thoughts and wishes.