Try to transition her. My LO wasn't quite as distressed by the switch, but to begin with, she seemed unable to keep the 6+ ones in her mouth for very long. I stuck with the original one for night time, naps, and if she needed soothing, but then gave her the 6+ ones during the day. First step was letting her play with the dummies, as when she would see one she would put it in her mouth (even if she had to take another dummy out to do it) next step was to make the new dummies the perm day dummy. When she was fully used to it, I got rid of the old ones.
You could try her with Avent ultra air dummies, the teats look similar to mam 0-6 dummies!
my son used to only take MAM ones, but now he has TT ones and doesn’t like MAM anymore.
I think the shape on the 6m+ ones is just so they are less likely to fall out their mouth