Newbie help

I hope noone minds me posting, but I'm a newbie and would love some help and advice.

I've been slightly overweight for the last 5 years - nothing drastic, but I can't shift it. I'm always tired (bed at 9pm, sleep through til 8am easily if allowed, and could happily nap for a couple of hours each afternoon). I feel the cold terribly. I have spotty outbreaks, very dry skin, sex drive left the building years ago, I ache most of the time, awful pins and needles, vertigo etc etc. It all adds up to low thyroid.

My GP is fairly useless. I managed to get her to test thyroid function several years ago, but she said the results were totally within normal and basically refused to consider that I had anything wrong.

After my latest failed attempt to lose weight, I'm going back to her and won't leave until she gives me some answers! So, my question is, what do I need to persuade her to test me for? I know a full thyroid screen and some vitamins (is it B12?), but specifics I can list to her would be great!

TIA!