Im 19 days into my cycle and i had sex 8 days ago, could this implanation bleeding?

Implantation bleed: Implantation bleeding is much more common on the internet than in real life. It occurs rarely and exclusively in someone who is pregnant. The only way to know if someone had implantation bleeding or just irregular menstrual bleeding is to wait and see if you are pregnant. If your test is positive then this was implantation bleeding. If it is negative then it is just irregular menstrual bleeding.

Possible: It's possible, but you'll have to wait and see if you start your period on time. Do you need to be thinking about birth control?