Help with weight loss

Without going into too many details why I’m thinking about asking my doctor for help with losing weight. I’ve gained about 20 pounds in the past 4/5 months. Also during those months I had no period. I have always had a irregular period, which I was told was because I have cysts. But that was the longest period of time. Gaining this weight has not only effected me physically, but mentally too. I’m not sure what my doctor could do but I just don’t know where to turn. I have been trying for about 2 years to lose weight & I only keep on gaining. If anyone has had help medically to lose weight please let me know how you went about it!