DD is 6.5 months and is gorgeously smiley but seems quite a lot behind other babies of her age in some ways. She only began laughing about a month ago, she can't sit by herself for more than about 10 seconds without flopping over, she's not interested in putting things in her mouth, she's not interested in food particularly (she'll eat purée if I feed it to her but doesn't watch us eating, doesn't grab food, doesn't grab the spoon), she can't sit in a high chair without getting really upset because she's unstable and she has rolled over no more than 5 times ever. I know it's not helpful to compare her to other babies and I know all babies develop at different speeds and times, but I just have a bit of a niggle about it.