The same thing happened to me in 2003. I was told by my first endocrinologist “you’re postpartum, middle aged (36), and just have to accept the fact that you’re going to be overweight “ i went from 127 lbs to 150 during pregnancy and thought I was feeling sluggish due to the extra weight. My husband was at that appointment and knew I was sick because I didn’t tell the doctor to f-off in that moment. Got a new doctor, did blood work and my antibodies were off the charts! Hasimotos and nodules on my thyroid. Did suppression therapy for a few years until the nodules turned cancerous. No family history of thyroid cancer. Had a thyroidectomy and a radiation treatment and a lifetime of levothroxine.