I'm afraid to gain weight

Long story short, part of my PTSD has to do with me being disgusted by body fat. But with my new therapist and my obgyn appointment recently I've been convinced I need to gain weight (I'm 93lbs).

I have this horrible fear if I have any body fat though I will be disgusting and unable to stop gaining weight. I'm afraid I'll lose my partner even though I know own that is an irrational fear. Has anyone had to lose or gain weight due to their poor eating habits? Does your body transformation leave you dissatisfied? Will it make my depression and self image worse?