Hpv vaccine ?

I just recently heard about this vaccine and didn’t get it when I was younger (I’m 17 now ) because my doctors never really brought it up or didn’t think it was an important vaccine really. Now I’m hearing about how you can get cancer if you don’t get it. I’ve only had one partner and he’s only been with me and hope to only have this one for the rest of my life. (Been together three years already) can anyone tell me more about the vaccine or if I should get it or not ? Is it too late once you’ve had sex?