Hi! I got my first snake, my gorgeous ball python, Eve, aroung 6 months ago.

She's had 3 sheds, and eats well, but at around seven months old she's only around 200 grams. Is this normal? I've never had a snake, but shes one of the best pets i've ever had, very curious and active when im playing with her, and her temperatures are fine, but her humidity is low at 40, i try to get it up, but it usualy only stays at 40. Any help?