It all depends on what state you live in. There is a possibility she could get in to trouble because she's 19 and you're 17. Can I ask why birth control was not used? Many times you can get condoms for free at the clinic. May sure to get some and use them so you won't have to worry about an unexpected pregnancy. Has she taken a test yet?
In most states theres the 3 year law. Your s/o once their 16 they can have a boy/girlfriend who is no more or less then 3 years difference in age.
The age limit for sex is 16 so as long as it was consentual, it should be ok. That depends on where you are. You will have to find out what the circumstances are where u live.
Let her know you are there for her, and talk about both of your options and see where it leads from there. Don't push anything on her just as she shouldn't push anything on you.
Most importantly, don't jump to conclusions. There's no point freaking out if there's nothing to freak out about. If you find she isn't pregnant, think of it as a second chance at a carefree teenage-hood for the both of you. You wont get a 3rd chance, so be more careful next time! :-) good luck