Is it normal to still be bleeding 3 days after sex for the first time? I know its not my period because I already had it this month.

Yes. It is not uncommon for women to spot for a couple days following intercourse for the first time. Please pay close attention to your cycle as well as the type of bleeding and if it continues for any longer than 4 or 5 days please see your primary care physician. If you are bleeding profusely as a result of intercourse, please see your primary care physician.