I put my penis outside v. No penetration. No cum. Just pre cum. Both are wet. We do it on 17/8 and my gf got period on 24/8. Possible to get pregnant?

Not pregnant. It is nearly impossible to get pregnant without penetration. Furthermore, the fact that your partner had her period means she is not pregnant.
Most likely not. The act by itself can put her at risk of being pregnant but since the time of the contact was not in the ovulatory cycle ( safe period ) and she saw her next period couple of days later . So she is not pregnant .