Mommy, hi! I want to know if it's normal that a 7-month-old baby isn't…

Mommy, hi! I want to know if it's normal that a 7-month-old baby isn't crawling and standing on all fours. It's just my first child and I don't even know when he should start crawling. Other kids look like they're already on all fours at 5-6 months old and crawling around. I'm starting to worry that something is wrong with my little one. I asked the pediatrician, she said let him play with a toy at a distance and let him crawl. But we can only do this, or is it normal?