Hi Lucy,
Be sure that you're taking the thyroid medicine and calcium 4-6 hours apart. More is better. Also, you might want to keep a food diary for a while just to be sure you're not getting too much calcium.
Cron-O-Meter and
FitDay have free online diaries that track many nutrients, but there are others available. I only take 200 mg/day, and some days, I just skip it, because I generally get enough from what I eat.
I take a ton of supplements, although I now about half as much as I was taking a year ago. I've tried to tailor my supplements to my specific needs and to what I know of my genetic wonks. A lot of what I take is based on research I no longer remember doing, but I have attempted to give up some supplements only to find I feel worse without them.
NAC is great. I don't do well on methylfolate (B9) or methylcobalamin (B12), so I take a B-complex that includes food-derived forms of both vitamins. The need for methyls really depends on which of the MTHFR alleles you got in the genetic lottery, and even at low doses, methyls make me sleepy and foggy. I used to take alpha-lipoic-acid with my acetyl-l-carnitine, but I've given up the ALA without noticing any change and I've cut back the ALCAR to 500 mg/day (from 2000 mg/day). I may increase the ALCAR again, because lately I've had some tingling in my feet. As to the D, I take nearly 8000 IU/day, but again, that's on account of a wonk in one of my genes, and I need that much to keep up the blood level.
You might want to read about Vitamin K, magnesium, zinc and ubiquinol. If you have hot flashes, pine bark seems to do the trick. (It is not a phytoestrogen.)
And since you have both chemobrain and thyroid issues, please get your ferritin checked. It has the potential to be a game changer. Sorry I didn't think of it before.