Gaining Weight on Purpose

Just wondering if you have ever worked with anyone with Amenorrhea. 3 years after my second child I still don’t have a period. I am finally at a happy weight and love my body. I am on the lower end of healthy BMI, lift weights and do yoga. Everywhere I read I am finding that I may have to stop exercise and gain a lot of weight. My BMI is 19 right now and I have significantly cut down exercise. If I have to gain weight what type of thoughts can help me? Right now thoughts would be I am getting fat, I hate my body. Have you coached anyone through getting a period back? Not even sure this is the right approach. Dr just wants to throw me on Birth control but don’t feel that is the right answer. I do eat a decent amount of calories for my size. Only 5’1 and about 105 lbs and probably eat upward to 1800ish calories.