
Ashley! Unfortunately, I'm even newer than you are because I was diagnosed today with Grave's Disease (overactive thyroid).
I can answer a couple of your questions, thyroid medication is safe to take during pregnancy. My endo told me today that it would be fine if I got pg while on the meds. (At least my med is)
Thyroid problems can cause problems ttc (if

isn't coming around regularly) and if you get pg, if untreated (Grave"s Disease) has a high chance of causing birth defects and miscarriage (I've had two since Oct 04). I believe it is similar for an underactive thyroid, too. (I would double check on the web about that, though).
I could be wrong with this, but my numbers "were through the roof" according to my doctors and I have a hyperthyroid. Did you have any other symptoms? I have hand and foot tremors (we thought I had MS), staving ALL the time, hot flashes, sweating like crazy, choking on my salvia, eye irritation, talking very fast and just very hyper in general. (That's why my PCP decided to check my thyroid, he said I was really hyper but didn't look like a hyper person.

)
I'm so sorry to hear about your brain tumor! That must have been so scary to hear! I'm glad it's not cancerous and hope you don't need surgery!
I look forward to getting to know you better!