Swollen lady bits

I am almost 21 weeks pregnant with baby number 4 and lately my vag area swells so bad from standing. I work full time, go to school and have 3 other kids so being upright is a must. Any advice or suggestions? Also, any tips on maintaining a healthy pregnancy weight. I’ve always gained the minimum amount just due to me having a fast metabolism but now I am up 20+ pounds at the halfway mark.