I know this is an obvious question, but why are you having unprotected sex when you're ovulating and most fertile when you're not trying to get pregnant? Doing this can and will end in pregnancy. You're honestly playing with fire doing that! No one can tell you if you're pregnant. Many things can cause irregular bleeding. Implantation bleeding doesn't usually last as long as that, it's usually just a few spots on your underwear or on the toilet paper.
All you can do is wait. If your period doesn't show then take a pregnancy test and you'll get your answer.
This spotting can be due to implantation spotting or intermenstrual spotting. Main causes of spotting between periods could be due to pregnancy, birth control pills, infection in an area of the body related to menstruation (including the vagina, the cervix and even the bladder). Other causes could be polycystic ovarian syndrome, diseases of pituitary gland, hormonal imbalance of estrogen and progesterone and uterine abnormalities like fibroid and cervical dysplasia.
You should get your pregnancy status checked. Hence to confirm the status of pregnancy, I suggest you to test for pregnancy by a highly sensitive pregnancy test 10 days post ovulation with a sensitive ( 20 - 25 mIU ) pregnancy test. Also then I would suggest you to get your serum HCG levels estimated since this is more specific than urine for pregnancy tests.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.