Pregnancy check up

I had close sex with my hubby though we didnt have intercourse bt while having close affair few drops of sperm came out and touched my vagina. It was on 19th February and my period is due on 6th of every month and till date I m not period.. M sure it was not intercourse.. just wish to know can there be any reason for delay in period or how can i check for pregnancy?? i have read on few sites that pregnancy test or blood test not reliable..