My bb is 8 months old. When I carry bb by the armpit. I feel bb is very soft like fragile. Is it not enough nutrients ? Bb is drinking and eating well.

Actually I know what you are talking about. My baby gal is very firm , but my nephew feels very soft. Can feel the difference. My nephew was slightly premature and only weigh 2.2 kg when he came out. There was a period of time his head keep slouching to one side and we were told to let him look at the other side more. Now even though he is going 8mo his head sometimes still slouch and he feels very soft. He cannot sit up unassisted for too long. Maybe you should see a PD and he can refer to a physiotherapist on this. You should let him have more tummy time. Tummy time let them strengthen their core muscles