9 month old not crawling

B • Mommy to 3 😊

My son just had his 9 month old appointment and the doctor asked if he's crawling yet and I said no and that he just started scooting backwards the other day. And she said if he's not crawling by 10 months he's gonna need physical therapy. Should I be worried :( he dreads tummy time :/ anyone else's 9 month not crawling or pulling themselves up?