Well, everyone else has already brought up your stance on abortion and how you want to make an exception for yourself etc... so let me try to help you on the rest.

I don't know where you live so I don't know what the legality on abortion is in your area. If it is not legal or she needs a guardian, she needs to find someone ASAP who can go with her to a clinic or start looking for states nearby where it is legal. In my state, you don't need a guardian and how expensive it will be is based on your income. As far as I know, the only state where it can be completely free is California (per a friend who got one there, things may have changed since then) so start checking around right now and see what your options are. This information is all based in the US, but applies elsewhere too.

Abortion is extremely uncomfortable. You need to be there for her. Do not chicken out. Especially considering how young you both are. It's incredibly traumatic no matter how much or little she wants to keep the baby because the minute she concieved her body started producing mass amounts of hormones that will affect her mood and emotions greatly.

However, should you choose to keep the baby or come to find that abortion is not an option, she needs to start taking prenatal vitamins now and check to see what foods and drinks are safe for pregnancy. She needs to book an appointment with an OB/GYN because it can take a while for some doctors to take in a new patient. Even if abortion is absolutely the only option you're thinking about, act and prepare as though you're going to keep it just in case things don't go the way you hope. If she drinks and parties and does drugs only to find out that she can't get an abortion, that is going to affect the growth of her embryo and you don't want to risk giving the innocent baby birth defects just because you never wanted it. This is from personal experience. I have had an abortion so I am well aware of the terror you both are facing right now.

I'm sorry this happened to you and I know part of that reason is failure in the education system. Precum can absolutely make you pregnant. You are still both very young and I know what it's like to feel invincible - until you're not. Take this one step at a time but do not waste time. Start your search for a clinic ASAP and get quotes. Find a trusted adult. And if you or your gf need someone to talk to without judgement, you can always message me. I've had an abortion and I'm currently pregnant so I may be able to offer advice whether she ends up keeping or aborting. Best of luck to you both.