Pretty sure the OP doesn't need a load of daughter bashing. Ranting about how stupid it was doesn't change the situation.
OP, ultimately, you won't know until she's due on and can take a test. All you can do is take it day by day and have a box of pregnancy tests in. There's nothing else you can do. All you can say to her is - it's done now, we have to just sit tight and wait. No point right now discussing abortions and whatnot you could be working yourself and her up about a situation that hasn't happened.
You're just going to have to wait it out and see.
If she is pregnant, the best thing you could do is take her to an impartial advisory group that can talk her through her options and help her reach a decision in an unbiased way.
But like I say, you can only cross that bridge if you get there.
It's not actually that easy to fall pregnant, the timing needs to be right, the egg needs to attach, there's a whole bunch of stuff that has to happen. So one accident in a month is not the same as actively trying (or totally throwing caution to the wind). Of course people do fall accidentally pregnant but it's a probability chance now and the probability is on the lower end of the scale.
Hold your nerve, tell her to do the same. Wait till she's due on, test and if she isn't breath a sigh of relief and then have a conversation about proper contraception. If she is pregnant - you'll just have to face it down together with her.
Getting angry, distraught, ranting etc won't achieve anything.