My eldest son had severe torticollis as well as a deformation of the head. Unfortunately, several peds that we took our son to said that it was just a misformed head, sorry. Well, our ped finally came back from maternity leave and said that there was a severe problem and we went directly to Cook Children's. We had to put him in the helmet (which is a story in and of itself) for almost a year. He still has a major ridge on the back of his head (he's 7 now), but luckily hair covers most of that.
Ok, now that the "bad" news is over, here's the good news. You and your ped caught it in plenty of time to work around the skull reformation/deformation. Turn her constantly, so she's not laying in one spot constantly, give her plenty of tummy time (without sheets/blankets bunching up around her) and work through the PT. It does help, I promise.
I would do my best to avoid the helmet at all costs (i.e. really work through the PT), especially if she has skin sensitivities, et al. Brandon, my son, had major problems with the helmet- major rashes, breakouts, and other skin irritation. After a year of being in the helmet (and shelling out $2200.00 for the helmet alone), they told us that we needed to get Brandon in another helmet. We didn't see the results that we had anticipated, so we decided along with the neurosurgeon, to forgo another year of the helmet and just focused on the PT. BUT, let me also interject that he was almost a year old when they got him into the helmet, so he wasn't an "ideal" candidate for the helmet.
Ok, that was really rambly, but I just woke up and haven't had caffiene yet. Sorry! :-/ I hope that helps a bit.