Weight Gain - 20 weeks

Erika
Hi everyone, I was just wondering if this is normal. I was 113 pre pregnancy, actually was probably 105 a few months prior as I was dieting and on a strict workout regimen. I gained 5 lbs in the first trimester and then another 7 lbs at my nov checkup, and today just gained another 12 lbs!!!
I'm 20 weeks. Is this normal? My midwife says I should watch my carbs and liquid calories. I feel as though I'm the type that needs to workout a lot even though I don't eat a ton. I track my calories and I eat around 1700-2000 cals a day but too tired to do too much working out besides walking here and there. Also I had 2 wedding celebrations, a birthday, and then thanksgiving which means I've been eating a lot. 
Just want to hear others input. First pregnancy for me.