there is physio you can do to help roll her .. my friend had to do them but he hated it so much she gave up and let him do his thing ... he is perfect now .. and the weight seems fine

if she seems like she wants to crawl ,encourage her to .. DS rolled early everywhere .. it was the only way he got around..and cralwed at nearly 6 months .. each bub is different and if she is holding her head up at tummy time and is happy and content and weeing and pooping and smiling and interacting , i wouldnt worry at all ..

another thing also is girls tend to gain motor skills a tad later than boys ..so she may just be better is other areas xx