I have thyroid problems and experience the same symptoms as you. When you see your GP, ask for a scan. I had bloodtests to test hormones, which fell within the normal ranges. It wasn't until I had a scan on my lungs that my enlarged thyroid was picked up. My GP then referred me for a thyroid scan which showed a number of nodules in both thyroid lobes. I have an appointment on Wednesday morning with an endocrinologist to see what we're going to do about it now.

Good luck.