My DD just turned 8 months and she can sit up pretty much unaided now. She can roll back to front although she doesn’t do it very often, but I have seen her do it. She HATES tummy time, like cries as soon as I put her on her belly. I try to encourage her to do it with toys, singing and physical touch but none of it works. My friends have babies a similar age who are crawling and pulling themselves up so I feel like we’re tracking behind. Any advice?