We've been at it for 7 months ?and we're standing on our feet, but we …

We've been at it for 7 months ?and we're standing on our feet, but we still haven't mastered sitting and crawling. We learned to get up from the floor only last week. It stands everywhere and in the crib, getting up from the floor and holding onto the sofa from the ground. Here's my question, is it dangerous for the back, so long?