What causes sudden drop in TSH?

I have been on Nature Throid for past year after switching from synthroid. Recent lab results: TSH .03, (was over 10) Free T4 .095. Doc forgot to test Free T3, but the last time it was higher than normal range because I had taken it before the test. She has lowered my dose, but I'm feeling totally hypothyroid. I keep reading that the TSH test is useless, but I feel like crap since that number has tanked and all other numbers have remained the same for the past year.  I'm not sure if maybe my symptoms are something else?? Constipation, fatigue, depression are a few of my symptoms. Body temp fluctuates throughout month. but I'm at my warmest point now, 98-98.5.  Could it be adrenal or pituitary issues going on?  I have been under chronic stress the last few weeks with my husband's health and our financial future.