I am quite familiar as my wife is(was) hypo. She was in law school and we thought she was just tired. Eventually it became very difficult for her to study and she gained some weight. After over a year she was finally diagnosed with hypothyroidism. During that time she lost hair, had very dry skin and was extremely lethargic. They kept increasing her synthroid but nothing worked. She was eventually diagnosed with thyroid cancer which turned out to be malignant. It was removed in 2006 (at 25yo).
Now she's on ~275mmg. However, it isn't the end of the world. She gets it tested every so often and now she knows the warning signs of her hormones being out of whack (so do I!). We had our first baby last week, so life goes on.
My mom had hyper and couldn't sleep, dry skin, was losing hair. They had to destroy part of hers through irradiated iodine. She's one supplements now also.
Get your blood tested and take care of your diet and you will be fine.