Nothing to worry about, Mummy! Every child grows differently, milestones are just guidelines to help you understand what to expect in the coming stages - but there's nothing wrong if your child doesn't hit a milestone before the expected age, or if he skips a stage :)
He is trying to crawl but haven crawl yet right? He can't sit well but already can sit right? He doesn't need to be able to sit until very stable b4 he crawl.
Yes it's normal! some kids skip a certain development. my child skipped crawling and when to sitting then standing immediately,
it's normal. nothing to worry about. they learn at their pace their own way. no two child is alike.
not to worry all kids grow up and blossom differently... nothing goes by the book really.