Late Period

My period is late by 8 days and the longest it has ever been was 14 and I had a miscarriage then. My girlfriend (we are in an open relationship) said I'm not pregnant because when you start having a lot of sex it will change your period.

8 days of lateness because of 3 times having sex in the month of August....I have taken 2 pregnancy test and they all came back negative. I have heard that I should wait 2 weeks to 1 month before assuming that I'm pregnant.

I would like some advice, please help!!!

I'm sleepy all the time, hungry, horny & gassy like all day!!!! This is new to me, it would be my 1st at 32 if I am!!