Sex health

My ex boyfriend and I are trying to make a a baby for 1 year now from last year and I haven’t got pregnant once. had sex recently on my ovulation day which is Wednesday 16/05/18 he cum twice and I’ve been having pain in my stomach now and then. I haven’t vomiting or morning sickness yet or idk if I’m pregnant is there something wrong with me why I cant get pregnant plz help me