Lots of people are told their blood tests are 'normal'. Before the blood tests doctors knew all the clinical symptoms and patients were given a trial of natural dessicated thyroid hormones based on the symptoms alone. Nowadays it all depends on the point were the TSH lies. This means thyroid stimulating hormone which leaves many people undiagnosed and unmedicated.
Ask the surgery for a print-out of your latest blood tests for your thyroid hormone with the ranges and post on a new question. If your GP hasn't tested your vitamin B12, Vitamin D (these can cause problems too if deficient) iron, ferritin and folate ask for these to be done. Just say that you are having troubling symptoms if he asks why you want them and you want to to rule out it's due to a deficiency in these vitamins/minerals. What time did you have your blood test for your thyroid gland?