anyone else???

I'm 5 months pregnant ( 20 weeks and 1 day) and have already gained 25lbs!!! 
With my first child (I was 19) and only gained like 30lbs total my whole pregnancy. My starting weight with my first child was 93 lbs with a final weight of 136 lbs at her birth.
This one is a boy and I have just gained weight like crazy. I'm 5' 1 and starting weight was like 104 lbs now I'm 129 lbs. Has anyone gained as much as me? Should I be concerned? 
Btw I'm 28 now. Does that play a factor?