Weight gain at 20 weeks

I’m 20 w 3 d and already have gained 18 pounds. My pregnancy started out as a twin but we found out there was an empty sac at 7 weeks. Anyway, i read that you shouldn’t gain too much too fast and I gained like 10lbs within the first 8 weeks. This is partly Bc I never had any morning sickness or food aversions so I was eating. Y doctors don’t seem to be concerned but I did read the heavier you are you’re at increased risk for GD , preeclampsia and a big baby. I’m halfway there and I just don’t wanna gain more than 30. Anyone else gain this much at 20 weeks??