I wouldn’t ask or bring it up. Plan B is pretty effective, and if it’s not, well you can’t change anything by talking now. Women may change their hypothetical plans when they see a positive test or ultrasound. Planning something now would be setting you both up for guilt and disappointment if anything changes. But she most likely isn’t pregnant as most women ovulate roughly 14 days after their last period.

It was dumb to assume she was on the pill just because she initiated having sex. It’s a hormone altering drug, not every woman in the world is on it. If you aren’t ready for a baby, you need to have your own birth control method every single time you have sex. You can’t just go around finishing in people and then expecting them to handle everything afterwards or be 100% for abortion.