How do I know whether the cum is from me or my boyfriend?

How do I know whether the cum is from me or my boyfriend?

Me and my boyfriend had sex, and we did the pull out method and protected ourselves. We used a condom. He pulled out on time before he was about to cum. There were no tears or anything. However, later when I went to the restroom, I see all this white stuff on my panties. Idk it was a bit more than the discharge I usually get . Could it be from me getting wet? I would appreciate if I got an answer.