At how many weeks will I know I'm pregnant?

I have no idea if I'm pregnant or not. I know, I'm stupid, I regret the withdraw method so much. But my period is late and I need to know what to do. But he knew exactly when he was about to cum and he pulled out, and I know the whole story about pre cum. Please help me somehow. We did the first withdraw method the 25th of last month and I was supposedly not fertile then, but I don't know now