missing period &precum HELP

I'm very paranoid at the moment because I haven't gotten my period this month and I just started to be sexually active with my bf. I was a virgin and we did it with no condom. He didn't cum inside me at all ! But before we had sex I was giving him a BJ lol . Is it possible that when we had sex all the precum was gone after I gave him a BJ? He didn't cum either during the BJ. 
And when you guys first lost your viginitys did you guys your period the month you were expecting it or after a month or 2 ?? HELP PLEASE !