I don't know if you're in an after-care program like we are, but if you are, call your OT for some suggestions on how to help. He gets all over the house this way but his stomach drags along the floor. He also is pulling himself up and bearing more weight on his feet. He took 3 steps about 2 days after his 12 mos. Oh and my two cents, don't worry if Tristan doesn't crawl, lot's of babies don't crawl and become earlier walkers.
Every baby is different.
He too can sit on his own but has not yet pulled himself into a sitting position. He doesn't crawl on his hands and knees, but he inches himself along using his arms. I think its a great accomplishment that Tristen can walk across the room when you hold his hands. Zachary is still real wobbly when standing up.