I haven't been here in awhile, but yours was the first I read and my heart just ached for you and your family and I was flooded with memories of what we have gone through with our own dd, who is now a bit over three.
I don't want to bore you with all our details, but just to give you an idea that I can really relate, I will share a bit about my daughter's dental experiences. At less than two years of age my daughter began seeing a ped dentist after I noticed her front two teeth essentially looked like children with what I knew to be "baby-bottle-rot." I was horrified as they seemed to disintegrate on a daily basis. I was also night nursing and could not imagine weaning. to give you the summary, in the past year and a half we had caps put on both front teeth; ultimatlely had one tooth pulled due to an abcess; innumerable fillings; one horrible looking metal cap on an upper back tooth; and are now in the final process of putting sealants on every crack and crevice to try to stem the tide of this situation. I could so relate to your pain over the loss of "her beautiful smile." I remember crying in my husband's arms, feeling so responsible for those awful looking brown teeth. Maybe it is because they are girls, but I am embarassed to admit how I worried about this. I have to tell you that the white caps she now has on both her front teeth are beautiful. You cannot see any difference. (We did lose one and have to have it replaced, but hopefully, this one is on more securely.)
Now, how did we achieve all of this? Well,we did have a semi-supportive dentist, who is very child friendly. I layed in the chair first and as gently as I could I wrapped my legs and arms around my daughter. Sometimes placing one hand over her forehead to keep her head still and my other arm wrapped around her body holding both her hands in mine. Is the effect still like a papoose? Yes, I'm sure it is, but I would much rather my loving arms were around her than her being strapped to a board. We were even able to do this when she had her tooth pulled. In less than five minutes the tooth was out. I don't think that I ever could have left her alone, I have a hard time imagining any dentist requesting that you do so, but this must be your personal decision. Perhaps, if you end up having to use a dentist there, you could just ask them to try it this way, who knows they might be pleasantly surprised at how well it works. Also, I would usually tell a story or sing to my daughter, and that would sometimes help. I'm not going to lie, there were times we both left sweating and hoarse, but we always tried to do something special afterwards and somehow we are getting through it. I know there are posts in here from smilemomma talking about the use of Roman Chamomile oil (I think) to help calm children during the procedures. I have never had success locating it, but you may want to check that out, as well.
I am happy to report that at today's dentist appointment she barely cried at all and took deep calming breaths (something we've talked about in advance) when she got scared. We all agreed it was our best appointment yet. I don't know if any of this helps, all I can say is that you do get through it, and their teeth can look beautiful again. I hope that you hear from the dentist in CT soon. I guess that would be my only word of caution is that I was always surprised at how quickly things could develop and advance in my daughter's mouth. (Not that you should take her to someone you are not comfortable with, by any means.) I'm sorry I didn't address the thrush, but I have little experience there. I'm sure there are tons of postings on this on the breastfeeding forum. My very best wishes to you and your family. Let me know if you have any questions about anything I wrote. Sorry it got so longwinded! (P.S. Yes, she still nurses!)