My positive OPKs always fall between cd13 and cd16 (so far, I've only tracked it the last 4 months).. I would like to try for 2 attempts (preferably O-2 and morning of O) but of course I don't know what O-2 would be since my positives are never on the same day from one month to the next. How do I determine when to BD to get as close as possible to O-2? The only thing I have noticed so far is cm increases about 2 days before I get a positive, but what if I go by that and it turns out I don't get a positive until 4 days later? Does that mean I only get one real attempt on morning of O or should I dtd every 2 days starting at cd11? I keep racking my brain on this.

