What's normal?

Since we are new at having an infant, we really have no idea what "normal" is. But for Lillie, I think normal is going to be sitting up all by herself before she rolls over...I cannot get this girl to roll over. She is on her belly most of her waking (minus eating) day. This last week we tried a bit more back time to see if she prefers rolling from back to belly...nothing. She does, however, love to try to sit up on her own. She can do a few seconds at a time. I'm sure her cloth diaper helps make a nice wide base to sit on.