Possible to miss ovulation using OPKs?

This is our 3rd month TTC and I decided to use OPKs for the first time because I found Clear Blue digital tests expiring and on sale for 1/2 price (expiring may 2015).  
I have a fairly regular 26-29 day cycle and usually get EWCM around ovulation which I haven't really had.
I'm now on cd 15 and I haven't received a + test yet. Is it possible that I missed ovulation? Did I not ovulate (yet)? Are the tests faulty? What do you think?
Extra info: I travelled to an 11hr time difference for last week and 1st week of this cycle and had a yeast infection after my period which I treated with a 1-day tablet around cd 11. I've been testing every morning with fmu. Worried that we aren't conceiving be I'm not ovulating.