Well, if you want to know if youre really pregnant, im sure there are test kits available in your area, which are easy to use, and moreoever they show up positive in 10-30 days from the last periods. So its easy.
But however, if you are worried who is the daddy for your baby, its better to decide earlier what you want to do, in case you are diagonised pregnant.
The chances of pregnancy does not depend on a firm or a torn condom but the duration of making love from your last date of your previous periods. If you know how to calculate it, then it may be easier to calculate your possibilities.
Anyway good luck. But in the future as far as possible, stick on to people you know well, due to too many viral infections around. You know what I mean. Youre too young. So better protect yourself to live longer and happier.