My period ended on cd6, had a positive opk on cd8, i just took another positive opk on cd12, i see my ob soon to ask. what could the problem be?

Probably no problem: So the way ovulation prediction tests work is by detecting the LH surge. That you detect the LH surge when it first appears is critical. Many women do not ovulate at 14 days, some ovulate on day 10 or 11. The LH surge tests positive for the first time 24-48 hours before ovulation. After that, LH will remain positive until your cycle starts again. So after one surge, no further testing is needed.

Implantation: Some women have bleeding when the pregnancy implants which mimics a period and some drugs will cause a false positive pregnancy test. Your OB will be able to tell you for sure. Good luck what ever you wish.