Pregnancy pre question important?

I had with my gf about a week ago and the condom split and i didnt notice for a while, i didnt *** fully cos i noticed it split. i also stuck it in her without it a couple of times but basically pulled out after cos i was drunk and basically horny lol. Anyway she started stressing that yesterday was when she expected to come on her period, and now its the day after and she still hasnt come on, i was gunna get her a pregnancy test thing but good ones are like 12 pounds which we dont have, and i dont want to tell anyone so i can borrow money. what are the rough chances that she is actually pregnant. she doesnt want to go to her doctors yet for some dumb reason.