i started my periods a few years ago and they were always regular. but ever since i got together with my boyfriend about 6 months ago, they have become irregular. they are often late and this month i have missed it completely and havent come on yet though my next period is due in a few days. me and my boyfriend havent had sex but have had oral sex, joint masturbation and dry sex. all unprotected. im petrified of being pregnant. i dont want to buy a pregnany test. what else could these irregular periods be down to?

i would really love someone in the medical profession's help. thanks : )