It is complicated. When blood tests are due it should be the earliest possible, fasting and allow a 24 hour gap between your last dose and the test and take afterwards.
Levo should be taken first thing on an empty stomach with one full glass of water and wait about an hour before eating.
You have to put a short history on your Profile so that members have an idea of your journey i.e. when diagnosed etc.
If you were diagnosed two years ago, I'm assuming you were o.k. on the 100mcg.
If you began to get symptoms after you'd been stable on your dose of levo, the doctor should have increased (many think if bloods are in range you're on sufficient - not true) your dose until your TSH is 1 or lower and some need it suppressed.
(I am not medically qualified and have hypothyroidism which was undiagnosed/untreated).