I had oral sex with my Girlfriend. She rubbed my penis over her vagina. I didn't ejaculated but there was precum. She missed her periods and its the 7th day of delayed period. We did pregnancy test yesterday, i.e. On 6th night and another one on morning of 7th day. Both resulted "negative" After we had sex, next day she got periods and this is second missed/delayed period. Should I be worried about pregnancy? Kindly help.