I'm 21 weeks and I've only gained 10 pounds. If you are worried you are gaining to quickly you can always to little 15 minute walks throughout the day. That's what I have been doing and it's been working.
20 weeks and I have gained 14 pounds... No body has say anything to me, I eat what I want but I don't eat fast food I also go to the gym or do Pilates at home when I can't make it
I've gained 15 pounds @ 20 weeks .
I think it's fine and normal if your doctor/midwife didn't seem worried or upset, every pregnancy is different.
Just eat healthy and stay active :)