Glad to see you post here.
In my limited experience, 125mcg is a monster dose to start someone off at, which concerns me. Starting with too large of a dose can cause heart palpitations, anxiety, and a host of other completely avoidable sides. It could also turn you off from seeking treatment which isn't desirable at all. Standard protocol is to start someone off at 25mcg and go up by 25mcg every 6 - 8 weeks each time testing TSH levels to see how the patient is responding. 125 might be the dose you end up at, but after a year or so.
I started feeling the effects of T4 (Levothyroxine, Synthroid) after 7 days but figured it was just placebo. After 10 days, the change was unmistakeable. Waking up in the AM was easier, I wasn't dead tired at night, my digestion was greatly improved, etc.
Good luck and post your TSH levels once you get them, I'd be interested to see where they were.
<---------- Not an MD