Are u covering your bases? Have sex every OTHER day from day 12 thru day 20 of your cycle. Are you taking antihistamines? They will dry up cervical mucus. You might go ahead and get an ovulation predictor kit to make sure that you are indeed ovulating.
STOP TRYING! its sounds stupid but for 3 yrs we tried with 1 miscarriage in that time and then we quit trying and gave up and guess what happened I was pg 2 months later I think it was because i was relaxed