D.G.
C.,
My 7 year old started crawling at 6 mo., pulling up at 7, but didn't walk until 13 mo. Yet, even now she can hardly walk a straight line w/ out tripping. My 4 year old didn't even start crawling until about 10 mo., didn't pull up until about 13 mo., maybe 14, then walked at 17 mo. Today, she's very athletic, coordinated & agile. Babies do all develop within ranges. I wouldn't start stressing over it just yet.
D.