I was sleeping in the same bed as my girlfriend when I was 16. My parents didn't care, and they're 70 year old libertarians.

They said age of consent was 16, and within 4 years is the romeo and juliet law in PA. They said it was my right to do as I wished, though they would highly suggest that I obtain protection if we were going further, because if I got her knocked up, I was out the door.

Seriously OP, this isn't worth fucking up a living situation/relationship, all you're going to do is make them dislike you and grow distant. The aim of being a parental figure is to teach. It's gonna happen anyways, in your house or not, but instead of huffing steam over what happens under your roof, you should try having a talk with them both about being safe. I'd rather have teens fucking in my home safely than have teens fucking in a car without a condom because they didn't wanna buy them or something, and then 9 months later get dragged into caring for a child that is not my own. That's just me, but I also don't intend to get divorced and be dating in my late 40s again either. You don't just keep getting chances that late in life at happiness :(