My 9 month old started crawling at 6.5 months, and when I think about his progress towards crawling I realize that compared to his older brother (who crawled around 8.5 months), he had MUCH more time on the floor (I was working when his brother was a baby, but now am a SAHM.) When I first started seeing him get into the crawling position, I'd sometimes place my hands behind his feet so that he could push against my hand and move his body. This seemed to help him get the hang of it, as he realized that if he applied pressure to his feet he could move. I also made sure that when he was on the floor I'd remove his socks so that his toes could be free to grip the ground.
I noticed a few posters suggest getting a walker, but the American Academy of Pediatrics does NOT recommend walkers, as they do nothing to aide in learning how to walk. They actually say not to buy them since the risk of falling down the stairs is high.
Like another poster said, I do not think your doc is trying to be a jerk. We pay them to tell us their professional opinions on our children's development.