TSH level is low, but T3, Free and T4, Free are within range.

If your TSH is high, that is hyperthyroidism. TSH is Thyroid Stimulating Hormone released from your pituitary gland in your brain. It's an indication of how much thyroid hormone your brain is asking your thyroid to make, basically. If it's low, then it's asking it to make less. If it's high, then it wants more. Sometimes, the thyroid doesn't always do what the brain tells it, and you get hyper or hypothyroidism (hyper in your case). This is sometimes due to Graves disease, which is an autoimmune disorder, but not always. Either way, the endocrinologist is going to put you on thyroid suppressing medications and try to get you into the normal range. You might also get another blood test to check for thyroid antibodies, to see if your issue is autoimmune or not.

You are absolutely right that symptoms of both hyperthyroidism and hypothyroidism can be very general and vague. They also don't always happen the same with everyone. Some people with hyperthyroidism feel very energetic (especially with mild forms), but others feel very tired because it makes it where they have difficulty sleeping and makes it where their body just never really slows down, so even when they do sleep, it's not very restful.

I'm sorry you have to wait so long to see the endo, but I think it's best to have this treated by a specialist because you're going to have to go back periodically for follow-up tests to make sure your TSH is in the target range and possibly have your medication adjusted. This isn't really something that a GP is going to do very well. It's just unfortunate that seeing specialists involves so much waiting to get in.

For your appointment, make sure you write down all your symptoms and how long you've been experiencing them. Also write down all your questions and make sure they are answered to your understanding.

I wouldn't worry. You've got a plan for the next step (seeing the specialist) and he or she will know what to do after that. Until then, try to relax and do what you would normally do.

you never answered the question. I have low tsh and high t3 and t4 and I was hoping you would say something useful.

Thanks, I appreciate it!

Is there anything in particular I should ask him? I'm not familiar with thyroid issues at all.

I'm sure he'll take care of it, but ask about other tests, such as an ultrasound, Radioactive Iodine uptake test (which measures how much iodine your thyroid is absorbing), and a thyroid scan.

Also ask if what long-term treatment plan your doctor would recommend.

Other than that, make sure you know how to take your medication, if prescribed, if there are any specific directions (I know there are for thyroid supplements for hypothyroidism, but I'm not familiar with thyroid suppression drugs). And if you have any questions about how the thyroid functions or even general questions, that's what you should ask. Write them down as you think of them so you don't forget. It's so easy to forget in the middle of the appointment.

Also, check to see if there are any pre-appointment things you need to take care of, like blood tests.