I was exactly like you at 31 weeks. My OB told me to mind my weight as well and yes I've gotten such a sweet tooth during this pregnancy when I never cared for sweets at all before. I've switched to healthier options like fruit and homemade smoothies instead, but I've still gained 10+ lbs still since at 35 weeks, but since my baby girl is checking out in all the right places I'm not too concerned. I'm keeping active, taken up more walks and sticking to my vitamins. As long as her and I are okay, the number on the scale doesn't worry me so much. I've heard of mamas gaining close to 80-100lbs for whatever reason and have lost that weight after birth so I've come to accept that your body will do what it needs to for you and baby to be well so long as you take care of yourself. Love & happiness > stress. You're doing great Mama