Could Inability To Crawl At 11th Month Indicate Hypotonia?

Hi...my 11 month old boy is not crawling yet but has good head control. He sat on his own for the first time in the last couple of days for approx 1 minute. He can put weight on his feet and stand holding onto the side of a playpen...He has a physio appt. coming up but I'm worried it sounds like hypotonia.