Withdrawal bleeding

Hi guys so I have finished the last pill In my combined pack and now am on my pill free week and I'm scared. I always get like this because I think my period isn't going to come and I associate that with being pregnant. I have four days usually after taking my last pill so I am due on Tuesday but I have a question to ask. PLEASE DON'T MAKE FUN OF ME OR MAKE MEAN COMMENTS: so I am a virgin but have done some things with my boyfriend. Whenever he goes to touch me I always make sure he hasn't touched himself with that hand or if he has no matter how long ago he washes his hands cos he knows that I worry (bless him) so I am almost 100% sure that no semen has come into contact with my vagina. But I have touched him before, he has come and then once he has left my home touched myself like 2hours later. None of this could make me pregnant I am sure of it, am I right? Also what could potentially make me not have my Withdrawal bleed if I don't get it this month?