Even though this thread went kind of off-track, I'm going to keep it updated (if only for the fact that lurkers will probably search and find it if they need it.)

DD qualified for speech therapy with the early intervention program. Right after we went to the appt, we went and got her tongue tie and lip tie clipped and she now has much better mobility with her tongue. The posterior tongue tie apparently caused an underbite. She's still not talking very much, but it's only been a week, so we'll see.