Weight loss

I'm currently 22+4 with di/di boys. I was a healthy weight before pregnancy and loss about 5lbs my first trimester. I was really happy to find around 15 weeks that I was able to eat and gaining. I had gained about 14lbs and then I got a sinus infection and loss  5lbs in less than a week. I'm stressing out bc I know how important this phase is right now for weight gain in preventing low birth weights. Anyone else have a significant weight loss and bounce back pretty easily? I don't have very big babies in general, ds1 was 4lbs @33wks and ds2 was 6.11 @ 39wks. Wanna give these guys the best chance.