First, congrats on your 50lb loss! That's huge!
I felt exactly the same in the first trimester. I was so nauseous and tired all the time, and the only time I felt better was when I was stuffing my face or sleeping
I started out at 223 and I'm up to about 242, so almost 20 lbs.
I think doctors are overly concerned about weight gain for overweight women during pregnancy. I'm not saying we should gain 40 lbs but 20 doesn't seem unreasonable considering:
7 - 9 pounds of baby
2 pounds of placenta
2 pounds of amniotic fluid
4 - 5 pounds of increased blood volume
2 pounds uterine enlargement
3 - 4 pounds of fluid in maternal tissue
1 pound of breast enlargement to prepare for breastfeeding
As long as you're eating healthy and taking care of yourself, both you and baby are going to be fine, even if that means you put on 20 lbs instead of 10. I know for me, it was really hard NOT to worry about the number on the scale, especially when it went up 3 lbs in a week. But I tried to not beat myself up about the weight I gained because the stress of that wasn't really helping me either
Best of luck and wishing you a happy & healthy 9 months. If you need anything, feel free to pm me. xoxo