Which thyroid tests were done? Sometimes just the TSH alone doesn't reveal what is happening. Were any other tests done to check hemoglobin, vitamin and mineral levels? Sometimes deficiencies can mimic other conditions.
I still do not believe the tiny amount of biotin you could possibly absorb from shampoo and conditioner could have any effect on a test.
Sue

Jess, did you tell your doctor about using hair products containing biotin? Have they suggested re-doing the tests?

@jenglish208 I agree with @sueinmn, I doubt that the shampoo would make much of a difference. I take biotin tablets and was told by my endocrinologist to stop taking them two or three days before testing. It's not the thyroid that's affected, it's the test.

As @colleenyoung mentioned, you should probably mention it to your doctor and find out from them if shampoo and conditioner could be absorbed into your system enough to affect the test and if so have them redone. If your doctor says that could affect the test I hope you will let us know, especially if you have the test redone and the result is different.
JK