8 month old still not crawling

My 8 month old daughter still isn’t crawling. She can get up on all fours, get to a seated position from laying down, she will take like 2 or 3 “steps” of actual crawling, but she basically just army crawls or rolls to get anywhere. I can tell it’s frustrating her. She will get in the position and just cry cause she can’t figure out what to do. Does the same thing at night - all night. She gets tons of floor time and everyday I set up toys or books to try and coax her into getting to them.

Just starting to get worried - a friend of mine has a 7 month old and she’s already crawling and pulling herself up on furniture - even though I know all babies develop at their own pace and the age range is pretty wide.

What age did your baby start crawling and do you have any tips on how to help my baby along?