L.W.
Don't fret...my first baby rolled over at 5 mos and was walking by 9 mos and my second didn't start rolling until 8.5 mos and walked at 14 mos. My third was in between her brothers. There is no set age of when kids do things...well nothing written in stone anyway. My grandaughters(twins) one rolled at 5.5 mos and the other at 6.5 and they have just started crawling at 8 months. It's not a contest. You shouldn't worry unless she doesn't start rolling by 8 months. She may be like my 2nd son and be a little lazy. Calm down and work with her. She may be getting stuck at half way. Who knows, once she rolls she may start crawling soon after...then your hands will really be full