They didn't test your TSI antibodies. They tested your TPO antibodies. They are high which means you have Hashi's - aka Autoimmune Thyroiditis.
With Hashi's, you can swing from hypo to 'hyper' (although not true over-active thyroid) and back through euthyroid to hypo thyroid. And, given your history, it sounds as if you were hypo at some point, but nobody gave you a test.
On these results, it looks like you're just coming down from a 'hyper' swing. These happen because the immune system attacks the thyroid, kills a few cells, and then the antibodies come in to clean up the mess - that's when they're highest. But, the dying cells have dumped all their store of hormone into the blood, which means that blood levels of FT4 and FT3 go very high, which means that the TSH drops.
But, these high levels won't last forever. The extra hormone will be used up or excreted, and you will gradually descend into hypo. By the time you see the endo in February, you could very well be hypo. So then, you will need thyroid hormone replacement - the famous levo that we all talk about on here.
As for the cancer idea... All I can say is some people do talk a load of rot! I've had Hashi's for many years, and my thyroid is now all but dead, due to the immune attacks. But, there has never been any question of cancer. So, don't worry about that.
Neither are you at any risk of thyroid storm, because with Hashi's, levels never get that high. So, it's not such a black picture as it has been painted! Your doctor obviously doesn't know very much about thyroid, but that's normal. None of them do! Here's hoping he's referred you to a decent endo!