Did he not pull out fast enough?

I know its not a reliable form of bc but we are in the mindset that if it happens it happens and we will be happy. Anyways i was approaching/in my fertile window having stretchy cm and when he pulled out almost everytime we had sex the majority of it endes up on me but 2/3 times it felt wetter than normal down there after sex so im wondering if there is a way to tell semen from cm.