OK, I have had thyroid cancer - diagnosed November 2019 and got the full all clear back last March/April - and can reassure you on all counts.

The biopsy wasn't bad at all. It just really felt like pricking your finger on a needle. Yeah, it was the neck but they deaden it. The last one stung a little all right, like I could feel them sort of hooking something out but it was only for a couple of seconds and more discomfort than pain. 

Went straight back to work afterwards and was absolutely fine. 

Most forms of thyroid cancer are also not what you are probably thinking when you hear the word "cancer." The most common form has a nearly 100% survival rate amoung younger people and given that you mention two young girls, I am guessing you are in that "younger" group - under 50ish. Even among older people, the survival rate is really high. I got obsessed with reading studies and stuff when I was waiting for results and so on and I read more than one which ended with a comment along the lines of "we also intended to study deaths but we had to drop that part of the study because we couldn't find enough people who died of it to get stats." Chemotherapy is also rarely used.

There is one serious form of thyroid cancer but that is really rare, mostly a disease of older people and you would probably know if you had it, as apparently, it's very fast-growing, so even if you do have thyroid cancer (and you probably don't; as I kept reciting when waiting for my results, "thyroid nodules are common, thyroid cancer is rare"), the odds are it's a relatively mild form. I know cancer never feels mild, but comparatively.

This was my experience.

I was diagnosed in November 2019 as I said, had an operation to remove my thyroid and a load of lymph nodes on the 6th of January, 2020. I was in hospital nearly a week and was so bored. I felt pretty much fine once I got out of hospital, except some numbness/stiffness in the neck, couldn't really carry anything heavy and got kinda tired in the evenings. The last was for a couple of weeks after the operation. I'd get tired at maybe 9pm after getting up at 10am.

I took a month off work, because I am a teacher and really needed both to be able to turn my head easily and to be able to talk loudly - my voice was a bit weak too - but otherwise, I could probably have gone back after 2-3 weeks.

I now take medication to make up for the fact I don't have a thyroid, but it honestly has no effect on me whatsoever. Might have lost a bit of weight on it or have a bit more energy, but that is likely imagination/coincidence.

The following May I had radio-iodine treatment as my tumour was extremely large - 6.7cm and there was spread to some lymph nodes (this isn't a huge deal but increases the risk of recurrence). This was basically just annoying. I took a capsule and then had to remain in isolation for two days and after that, I had to restrict my interactions with people for two weeks. The reason for this was their protection, as I was radioactive, not that I was at any risk myself. The worst outcome of this was probably that I got a massive nosebleed about 10 days after the radioiodine treatment.

That was that really. I'm fine. The worry is the worst part of it really.

By the way, I think it is between 5% and 15% of thyroid nodules that are cancerous, so the odds are very much that it's just a benign nodule. Something like 50% of people have a thyroid nodule and I think they are more common among women than men. Ones large enough to be seen or felt are less common but they are still pretty prevelant and the number that are cancerous is pretty small.