3rd trimester and only 13lbs up?

I'm 32 weeks 3 days and started this pregnancy at 147lbs. Today I weighed in at 160lbs. I had the Dr. measure the baby last month when I saw her because I keep getting comments about how small I looks. She said the baby looks to be measuring right on target. With my first baby I gained 35lbs. Started at 140lbs and got up to 175lbs (41weeks) so I can't help but think something is off.

I've been having issues lately with sour stomach BUT I do eat 3 square meals a day, plus a snack, plus a dessert of some sort.

I've also developed diarrhea this week by and think it may be brought on by stress. My neighbor has been harassing us and it's really been getting to me so my body is reacting this way.

I'm going in for a check up next week but wanted to ask if anyone else has experienced this or is currently experiencing anything similar?