Go ahead, do it. Cum inside her. You know you want to. When you first slid your dick into her soaking wet cunt, you thought that you could pull out before you made any life-changing decisions, but now, with each deep thrust, your resolve is cracking under the oncoming feeling of a good cum. You just met her, and she made you promise to let her know when you were close so you can explode on her tummy or breasts or face, but now your desire to fulfill that promise is almost non-existent.
It would feel so good to empty your balls into her and see her look of surprise as she feels jets of your seed filling her up. So let go. Do what your body is increasingly insisting you do. Seed her, claim her as yours, make her carry your baby whether she wants to or not. You can feel how badly you need to let go. Do it. Knock her up and watch her body change forever.