There could be lot of reasons for the above sign It could be because of a local abrasion just as can happen anywhere on the body or a problem higher up in your genital tract it is not likely to be related to the bicornuate uterus
but could be due to the contraception
u r on. Anyway no need to be very stressed but consult a gynaecologist if it continue to happen or if u r not up to date with your cervical smears. Best wishes.