Cramps after conception

Had sex during ovulation at the beginning of this month and about a week later I was getting an occasional pulling sensation on the left side of my stomach. I've also been feeling very bloated and tired- also the left side seems more bloated than the right. Naturally I guessed I could be pregnant so I  took a test this morning (3 days before period is due) and it was positive! However I've been getting mild cramps this afternoon as if I'm about to get my period! I've been freaking out all day because of the positive result and now I'm worried that something could be wrong? Anyone else experienced this?  I haven't told my fiancé yet because I don't want him to be disappointed if something isn't right. Going to book an appointment with the doctor tomorrow!