How many of you knew?

How many of you knew from the time of conception? This sounds crazy but with my daughter I got pregnant from a one night stand and had no symptoms other than missed period. So I've had sex on 4 fertile days so far tuesday(first fertile day), Wednesday, Friday and today. Well the reason I have my suspicions is because today I got way too emotional and weepy and it was over things I normally am calm about. Did anyone else have any odd symptoms or just KNOW? Feel like I'm going crazy