Probably the Zoloft was from a doc who thought it was your hormones ( if you had a partial hysterectomy, did they leave your ovaries? If so, the doc might have been thinking your ovaries were suddenly producing smaller amounts of hormones; antidepressants are sometimes prescribed for hot flashes from that cause).
But the testing positive for low thyroid is where I would tend to focus if I were you. There is more than one kind of thyroid test, and you should ask for them all. I'll drop a note to Barb here at MedHelp who is the maven of all things thyroid, and point out your post so she can give you some more helpful information than I can.
Wow - I'm sorry you're going through this. I can identify because I've "been there, done that".
Can you, please, tell me what test(s) they did to check your thyroid? It would be very helpful if you could post the actual test(s), along with the result and reference range(s) so I can see where your result(s) fell within (or out of) them.
I'm not sure who told you that estrogen "cancels out" a thyroid test, but that's certainly not the case. All of our hormones have to be balanced or we aren't going to feel well. If you need estrogen, only estrogen will fill that need; if you need thyroid hormones, only thyroid hormones will fill the need, therefore, if your thyroid was really low (meaning you have hypothyroidism), they should have done further tests to determine the cause (autoimmune or other) and started you on replacement hormones.
It's not unusual for antidepressants to be prescribed for someone who has hypothyroidism, instead of the proper medication being prescribed.
I'll be able to tell you a lot more, once I know what they actually tested and what the results were.
I'm sorry you are dealing with all this. I think it's important to know that even though you still have your ovaries, they typically don't function normally after hysterectomy. This puts additional stress on your other endocrine glands, especially thyroid. The ovaries of women with all their female parts produce higher levels of ovarian hormones than women who don't have all their parts, especially testosterone, some of which the body converts into estrogen as needed.
With such a low testosterone level, it makes sense that your doctor Rx'd some T cream. But it sounds like it made you lose hair. Did you get any benefits (e.g. stable blood pressure, better body temperature regulation, better mood, higher stamina, etc.)?
Estrogen has been shown to mitigate some of the increased health risks associated with hysterectomy and impaired ovarian function or ovary removal. And I can attest to its benefits as far as symptom improvement (post-hysterectomy).
When your thyroid was low, what were your lab results? Personally, I like to see results for TSH, free T3 and free T4, and (at least initially) TPO antibodies to assess health of my thyroid or efficacy of thyroid meds. As far as your statement that estrogen "apparently cancels out a thyroid test and makes thyroid look normal", that does not line up with my understanding. Estrogen (and oral probably more so than transdermal) will increase hormone binding so your thyroid results would tend to be worse (more towards hypothyroid) because your body's thyroid hormones (or thyroid medication) gets "bound up" making less available for your body to utilize.
If you post your lab results, we can provide some input.