It is very common to have bleeding
when you begin having intercourse, and I recommend that you speak with your doctor
about your concern. Most women will have bleeding after the first time due to rupture of the hymen, the membrane that covers the vagina and usually only gets ruptured during intercourse (though trauma or tampons can also rupture it). It is also possible to have bleeding due to tearing of the vaginal tissue. The vaginal mucosa can be quite sensitive, and may be tearing; there can be a lot of friction especially in particular if your boyfriend is wearing condoms and you do not have enough lubrication. Avoiding intercourse for a couple days to allow the tissue to heal and trying synthetic lubricants may help. Many young women also have more sensitive cervices which can cause a condition called cervical erosion where the cervix becomes irritated and bleeds. Certain infections such as yeast infections that irritate the skin can cause it to be more sensitive and bleed during intercourse, and lesions in the vagina or on the cervix such as small polyps can also become irritated and bleed. Conditions related to your menstrual cycle, such as endometriosis
, can also cause bleeding. If you continue to have bleeding during intercourse, I would recommend you speak to your doctor so they can get a better sense of what your symptoms are, do a physical exam, and discuss safe sexual practices and what kinds of screening testing you should get now that you're sexually active. You should also discuss with them getting the gardasil (HPV) vaccine if you haven't gotten it yet.