Hi,
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If you were sexually active during your probable ovulation days, then chances of pregnancy cannot be ruled out. The absent periods, and heavy bleeding after missed periods could be indicative of possibility of a miscarriage. It is difficult to comment without examining you. You should consider visiting your doctor/gynecologist for examination to see if cervix is open (open os) indicative of possibility of miscarriage. An ultrasound scan done will help in showing if there is ongoing miscarriage and retained products of conception still inside uterus causing the bleeding to be persistent. Request for a repeat examination, ultrasound scan and serum/blood HCG level estimation to confirm the exact cause for the bleeding. Appropriate treatment measures would be started to help you. All the best.
If pregnancy gets ruled out and if you intend to remain sexually active, consider visiting your gynecologist to get started on suitable regular birth control measures to be protected (after your periods/withdrawal bleeding). Be regular with birth control use as instructed. Avoid having unprotected sexual contact.
Take care.