Hmmm ... I see what you mean. OPKs are usually pretty good at detecting that LH surge and you should definitely see a result from that. It is possible to have periods and not be ovulating.

I don't know how long you have been trying but there is a blood test that your doctor can do on day 21 of your cycle (assuming you have a 28 day cycle so the actual day may vary) which will detect whether or not you have ovulated. That little test may help a bit ... at least you will know whether it's happening and then you can start looking for the right time.

Maybe have a chat to your GP?

I never actually took temps but some girls find them reliable. I did chart my cycle, using a guide I found in a book on the Billings method. It did help to work out my cycle over a period of time.

Good luck!