I Am A 32 Year Old Female Trying To Conceive

I am a 32 year old female trying to conceive our second child. My husband and I are both in the healthy ranges on all the fertility blood work... the issue is that I do not ovulate and have irregular cycles. My doctor prescribed letrizole after three rounds of clomid. I had eleven days of positive ovulation after being on letrizol and my cycle is due on the 24th however I believe it came today. Is this common or uncommon?