I commented on your other post too but just wanted to say don't get discouraged. I was diagnosed with hypothyroidism when I was 19 and it took awhile to get everything balanced out and where it should be. I'm 27 now and I've been on the same dose of synthroid for almost 5 years and am down to testing once or twice a year.
Its absolutely manageable and you can meet your goals regardless! Where theres a will theres a way!