OPK - no positive?

Looking for some help with opk. My husband and I are TTC baby #2, our son is 27 months old now. We were blessed to get pregnant quickly with him. We have been trying for a while to have #2 (this is our 5th month) and I've been using opk for 3 months because my husband travels frequently for work. I cannot get a positive ovulation indication! Using he Clearblue Digital smiley and am not getting a smile during 2nd OR 3rd month. I'm getting my period. It's regular. No reason to think I'm not ovulating. Using 1st pee of the day. Thoughts? We are trying to DTD every-other day regardless...