Period 5 days late

My period is 5 days late which never happens. I’ve had this metallic taste in my mouth for about a week now which I read could be a pregnancy symptom. I took a test today and it was negative. My boyfriend and I have sex every weekend, we use the pull out method (I’m not on any birth control) so I thought for sure I could be pregnant but now with the negative test I’m not sure what could be causing my period not to come. I’m so confused