Thanks for the query.
The bleeding you had after intercourse could be due to post-coital tear or there is possibility of some cervical erosion, polyp etc.
Getting periods in every two weeks is something abnormal.
So you once consult gynecologist, get examined and go for one ultrasound
to find out the possible cause for your problem and take treatment accordingly.
For more details you can ask me through: http://www.healthcaremagic.com/doctors/dr-sree-gouri-sr/63429