clomid and ovulation

I am on my second round of 50mg of clomid. I didn't do opk's the first month, but my dr wants me to use them so we know when I O. Last month, my 21 day labs showed progesterone levels of 26 last month, before clomid they were never even above a 1. So we know that I O'd, and the dr assumes that it was cd14 because I had a 28 day cycle.
So, this month, I am using opks and it's day 14 of my cycle and I still havent gotten a positive. Is it safe to assume in a 28 day cycle that O happens on the 14 day? Even if I'm O'ing late, shouldn't I still be seeing a positive by now? Or, is it possible that my cycle won't always be 28 days on clomid and maybe this is just a longer cycle?

[Elaine Brown, MD]

HI! Ovulation predictors are very difficult sometimes.  They never seem to work right!
Your period will always come exactly 14 days after ovulation.  So you can look backwards and see when ovulation WAS--and that is somewhat helpful.  Remember that your ovulation predictors are actually detecting the LH surge which happens 24-48 hours before the actual ovulation, SO if you surge on day 12, ovulate on day 14, you will have your period on day 28.  
If you  are taking Clomid on days 3-5 and if it works (your progesterone certainly suggests that) you will ovulate on cycle day 14.  Clear Blue makes a very nice ovulation predictor that is pretty pricey if you have extra $$.

Ask your MD about Femara.  I like it better than clomid.

Good luck!
Dr B