Lucy - did she crawl before she rolled or did she not move at all til then?
Olivia was a total non mover. She sat unassisted very early (about 5 months?) and then just never moved! We taught her to roll over at 11 months. And then at 12 months she finally started to bottom shuffle. Never crawled at all. Didn't pull herself up onto furniture till she was 15 months. Didn't walk till she was 20 months. BUT she was talking very clearly in 2 word sentences by 14 months. So I reckon she just focused on all the verbal skills rather than the gross motor. (Like me, too busy gas-bagging, LOL!)

I should add, I'll admit to being worried at the time. (She was my first.) But she is perfect and now physically very adept , very physically coordinated and dexterous (she is nearly 4).

It is totally understandable to be concerned. But in hindsight I know you don't need to be!