Angel, i agree with you, actually different bbs have different development progress. my boy can flip 1 fr tummy to back at 2nd mth, but full turn only at 5 mths, sits up at 6 mths, but dislikes sitting and prefer standing, can jump actively in jumperoo, but cannot crawl at all, can even hardly dragging himself. just like you, i don't need to worry he is crawling everywhere, i only worry that he flips everywhere.