Okay, so I was never a teenage male (by virtue of never having been male), but I'm going to comment anyway. I am probably way different than everyone else on this thread, but...hey, I'm going to go for it.
The moment you start saying something to the effect of "(Anything that might be construed as a reason to not do this)...but I want to have sex so bad!" is the point at which I check out of the conversation. I'm a little old-fashioned, but I like to think sex is not just a thing you do because there's a warm fleshy object and you want to get your rocks off. I hear there are plenty of implements for that, that are not living breathing humans. Sex is a statement, whether everyone wants it to be or not, and at the very least there should be some kind of trust established here.
I don't mean "get married before you have sex." I mean "at least you two should probably know what this means to you." Are you both agreeing that you're going to have a good time, not give each other herpes, and go on with your lives? Okay, at least have the conversation. Heck, if I went and picked up someone at a bar -- which I really don't do -- I'd still have the "okay look, we're going to use protection, if you don't like it we're not doing this, so on and so forth" conversation. Did you do any of that? Sounds like you just let the world go by and didn't really care if she was a human or a piece of meat.
So she's got a criminal record. Okay. Do you know what for? "A crime" can be anything from petty shoplifting because she had no money and was starving or something, to assault, to whatever else.
Do you know why this clearly sketchy girl wants to sleep with you? If you didn't find this out also, you have some homework to do.
Also...man, you're 17, why aren't you doing more productive things like figuring out what college you want to go to or something? Hell, I didn't date until I went to college, I knew I wasn't mature enough to know what I was doing. You have all the rest of your life to have sex; don't get in serious trouble because you want a quick screw right now. Pick a safer girl. Pass on this one.