Don't worry. My boy can walk a bit when he was 6 months (7+ months now), but he can't sit well (maximum 20 seconds), and he got only 2 teeth.
My sister's daughter is 1.5 years old but she has only 3 teeth. Every baby is so different in terms of development.
My daughter is also 6 months old, she still cannot sit, turn around, hold milk bottle. I heard people say that baby can turn around and hold things at 4 months. I am also very worry.
My boy is now almost 3 months and he is still unable to move his head up when he crawls on bed. Can anyone share with me when your baby is able to move his head up when he crawls?
3 months is still very small so no need to worry, I think most babies can hold their head firm at 5 mths or so, as for crawlings, it all depends, some babies skip the crawling stage and start walking from 9 months or so ... for my baby, she started to crawl at 9 mths. Every baby is different, relax and don't be too worry.