I have the fear, too, and I worked as a Vet Tech for 15 years. Can't remember losing any to a spay, though. Just don't want to lose them.
I believe your BF lost his dog to anesthesia read that in an old post, if I remember correctly. And she was a Bulldog. Bull Dogs are brachycephalic (short, squished nosed) and that alone makes them a much higher risk for surgery.
Yorkies are not brachycephalic, but you can have pre-op bloodwork done to be sure she can handle the anesthesia. It does not show allergies though, but that would still be rare.
Don't beat yourself up about waiting. I think older Yorkies are at a lesser risk during surgery, as their livers are full grown and can better process the anesthesia. Also you allowed her to grow up, her hormones have kicked in and have done their many jobs, so she should do fine.
I'll be praying for her on Thursday. When I drop my dogs off, I will turn them over to God, as it is his decision whether to keep them with Him or give them back to me. I have the same thought whenever I have surgery, myself. It's the only way to calm my fears... Hugs to you... be strong for Poppy...
