Getting concerned

Anyone else's 9 month old not mobile whatsoever? I'm going to look into occupational therapy if she's not showing any improvement by 11 months I think. She still just sits there with no interest in crawling or anything. Still loses her balance & falls over while sitting sometimes. Doesn't seem to care to catch herself or be aware. Still forgets how to roll sometimes. She was rolling like crazy one day, then rolled off the rug & bumped her head on the tile accidentally which was a major set back. Now she refuses to roll all the way. I'm getting so tired of sitting next to her on the rug all day. She will scream if I am out of reach. I've tried everything to get her to move. Toys, food, me. Nothing motivates her. She has zero independence. I feel like I still have a newborn. This sucks🙁 My son was late too but he was army crawling by now, rolling both ways by 5 months, sitting perfectly by 9 months etc.