I'm A 21 Yr Old Blk Female That Has A

I'm a 21 yr old blk female that has a history of PCOS and diabetes. I was a heavyweight teenager and was diagnosed at 15. I lost 110 lbs (260 to 150) two years ago, and in the middle of my weight loss journey, I got pregnant, but unfortunately miscarried. I continued to lose weight after and now I'm at my target weight, my medical conditions have improved. I'm no longer on metformin for my diabetes and am getting my menstrual cycles on time monthly so I stopped birth control back before I got pregnant. I now want to gain some weight back, but stress, depression, and lifestyle choices have rindered it hard for me to gain any weight. What I want to know is there anything over the counter that I can use to gain weight (vitamins, protein shakes, etc)