Anyone have similar cycles and taking Clomid?

My cycles have ran like this: 29 days,34,31,29..and having a hard time pinpointing my ovulation..the last 2 months we missed cd15 and cd18..So I'm gonna make sure we hit those days..I started Clomid days3-7 and just finished my last dose on friday..I was reading somewhere that you usually ovulate from 5-10 days after your last pill..I can't really afford those opk kits right now..Sooooo I'm relying on checking cm and maybe trying to Bd everyday?? Any suggestions or Success stories out there with similar cycles?? P.S. I'm taking 50mg of Clomid