Doubt

I'm confused. All or most of the stories I read about Vitex are that it has worked for them and it has regulated the period. However, I started in December to improve and regulate more my cycles (vary from 33 to 48 or 50 days) and mine has delayed. I have hypothyroidism and I've been trying to conceive for 8 years. I was able to get pregnant once and loose. My last period was on November 24. I have done several tests and I am not pregnant. Anyone with similar situation??