What is this little flap of skin right at the vaginal opening? (photo)

When you have sex for the first time the hymen breaks leaving skin tags of varying shapes and sizes around the 360 degrees of the vaginal introitus. You are seeing one these tags. They are normal, every woman has them and they do not pose any medical concern. Of course, if you want this tag removed it can be done quickly and easily in the office.

From your pictures, it appears that you have excess hymenal tissue that may have been a band that broke upon first intercourse. It can be removed easily in your gynecologist's office with the proper equipment.If you want to do some research on the condition, it's "medical name" is hymenal hypertrophy.