lh surge @ 7dpo and cramps???

I am soo confused I posted a question a few days ago about 4 positive opks and negative hpt, but havent gotten any answers. My chart has shown ovulation @ cd 27 which is later than normal. Usually I ovulated anywhere from cd18-cd23. I have been charting for a year since my miscarriage (9weeks) in October 2008. I usually use opks during the fertile time since hubby and I have been trying again. We have only been trying for a few months now. This month I didnt use opks and was hoping if it was a more relaxed situation we might have luck. Stupid me pulled out the opks a week after ovulation and ended up get 4 positives in a row then the fith day was lighter??? I followed up with hpts but negative.I am currently 8 days late which would make sence if I ovulated late. I guess i'm just wondering if af is right around the corner why am I getting positive opks?? I do not take any medication nor have I been diagnosed with pcos. I have also been having cramps like af since 7dpo???? Anyone with answer it would be greatly appreciated!!