This is also my first child and I'm 17.
I'm 32 weeks and I've gained a total of 8 lbs... However baby is perfectly fine and I feel like I've gained at least 30lbs!! I've had nausea and vomiting my entire pregnancy, anything I eat comes up.. It *****!!
I'm 20wks and only gained 9lbs. Dr said as long as baby is healthy and looks good, no worries. They will tell you if there is anything to be worried about