I have just been diagnosed with hypothyroidism - I've been borderline low for a couple of years, but now the doc has decided she should treat it. I haven't yet been for my appointment to talk with her - just got the phone call to come in - so I'm not much help. Here is a link to a website with lots of good information.
Also, most of the women in my family have some sort of thyroid problem and they are all doing fine on treatment. Thyroid problems are very treatable, so don't worry yet. Talk to you doc, search out information, you should be fine.
http://www.endocrineweb.com/hypo1.html