hey- just wanted to let you know Truitt didn't crawl until 8 mos. he really didn't have much interest and when he did, he mostly crab crawled. however, if you saw my pp you know that once he started moving he progressed very rapidly. he was a beginning walker right at a year and a very proficient walker a month later.
additionally, he has always had superior fine motor skills for a baby his age- able to stack blocks and play with small, intricate pieces from a very young age. my pediatrician said babies either develop gross motor or fine motor and then switch. so tru wasn't a bi mover b/c he was taking care of fine motor development more so than things like crawling.
so, don't worry about charlotte. i'm sure she's fine. all babies develop differently and she'll get where she needs to be. i read that 18 mos and no signs of walking is the point to be honestly concerned. so, she's got quite a while....