hey there, yes it could well have been implantation bleeding, oh and congratulations on your pregnancy, it sounds to me like the father is your boyfriend seeing as you had your period after having sex with the other guy and before the sex with your boyfriend. I hope all goes well with the pregnancy, good luck and enjoy :)
you had a period after you slept with the first guy so very likely to be your boyfriends.
i would have to agree that it would mostlikely be your bf cause you had a period after the other guy
The blood may have been implantation bleeding. Since you had your period after you had sex with the first guy I doubt he is the father. When you get your first ultrasound you will get an estimated gestational age showing how far you are and should be able to find out around when you conceived. If you're still worried after that a DNA test can be done after the baby is born, but it sounds like your boyfriend is the dad!