I'd agree with the others.
Plus I wouldn't get too hung up about having to have a dressage-legal bit at this stage. Far better to have whatever most suits her and makes it easiest for her to learn that her tongue can remain comfortable underneath the bit, and then when she's a bit further along, think about whether or not it's dressage-legal.
With one of my gang who used to put his tongue over the bit quite a lot, three things made a big difference:
- raising the bit in his mouth a couple of holes (tbh, it looked TOO high for my liking, but it seemed to suit him and he was much less busy with his mouth as a result)
- using a ported bit, so that he had more room for his tongue (and it would have been more difficult for him to get his tongue up over the port)
- focusing on having only one active rein at a time and keeping contact as elastic as I could.