I've had thyroid cancer and can reassure you quite a bit on this one. Firstly, thyroid nodules are extremely common and most are benign and secondly, even if it is cancer, and it probably isn't, it's not likely to be anything like what you are thinking. The survival rate of the most common form of thyroid cancer is so high, it sounds ridiculous to even call it a survival rate. Like I got carried away looking at studies and stuff and there was more than one that had at the end "we also wanted to investigate things that led to a higher death rate but we couldn't find enough people who died of it to make any kind of stats."

It also rarely requires chemotherapy or radiotherapy. They just remove your thyroid and that is basically it. If you are at higher risk of recurrance, they'll do radio-iodine treatment afterwards, which would probably be quite a hassle in your case, as you can't be around small children for a couple of weeks afterwards, so they would have to stay with somebody or you would have to stay with your parents or something, but the treatment itself is just swallowing a tablet.

I am no expert and am really only guessing here, but the chest x-ray could possibly be related to the thyroid as I believe the lungs are the place it most common spreads to outside the neck, though even this is extremely rare - less than 5% of cases, I think - and it's still unlikely to be life-threatening or anything, at least not at your age. Thyroid cancer is way more serious in older people. In under 50s, there isn't even a stage 3 or 4. Everybody is considered stage 1 or 2, 1 if it is within the neck and 2 if it spreads outside, which as I've said, is pretty rare.

Of course you don't want any form of cancer or any health risks at all, but my experience was that I had my thyroid and a load of lymph nodes removed, was in hospital for a week, off work for a month (this was largely because I am a teacher and really need to be able to both turn my head easily and raise my voice when necessary; if I'd worked somewhere like an office, I might have gone back a week or two earlier) and then just got on with my life as normal. 

It's a year and a half down the line now, heading for two years, and the only ongoing issue is that I get some tingling/numbness in my neck occasionally, which is irritating, but no more than that. I had a couple of days after the operation when I didn't feel well, but I am literally talking maybe three or four days. I've been fine otherwise