I'm so sorry that Tatum is having such a hard time right now!! I feel terrible for her
If they do surgery for the teeth, they should do the spay at the same time. My maltese Emma was just over 6 months old and weighed 2.9lbs when she was spayed and she did okay. I don't know how bit Tatum is though. They should use sevoflourane or isoflourane gas. They wake up very quickly after surgery this way...