Can I be this unlucky?

I'm not sure if my girlfriend is pregnant...but I don't understand how this can be possible... Its been exactly one month since she last got her period. First of all we were both virgins; we both had anal sex (we've never had vaginal sex) and I bought the "thicker than usual" condoms, it was 2 days after her period ended, I never came inside and the condom never broke. Thing is, her period usually arrives 3 days or so before the normal period length. She's having period symptoms but...lucky me, most (if not all) period symptoms are the same as pregnancy symptoms...I know I'll have a mental breakdown if I realize i got a virgin (vaginal at least...) pregnant, and still is! =( what do you think? (honestly, I'm here just to read if someone just says she isn't so I can calm down...but I don't to be lied to either, so even if the truth hurts...please give your opinions). To be fair though, shes told me her period is irregular, but usually arrives earlier than expected....not later. Thank you.. :-(