So I decided to try ovulation tests this month (we are currently on month 5 of TTC). I usually have a cycle of between 27-30 days so started testing on CD10. I had fertile CM from around day CD13 until CD18 yet during that time I only ever got the faintest of faint lines on the OPKs. I am now on CD20 with more or less no CM. Decided today would be the last time this cycle I use OPK and the line is more or less the same as the control line, arggggh! What's going on? (we have BD on cd10, cd14, cd16 and cd18 so unfortunately haven't really kept to the DTD every 4 days as planned, whoops!).