Late period??? Help

Ok so Ive had a stressful month as it is but the last week was awful because I missed my period. The chance of me being pregnant was low we barely have sex and when we do we use condoms+pullout even while wearing condom but he did drip a bit on me few weeks ago not much at all but enough to make me worry when I missed my period. My period is ALWAYS like clockwork every 28 days and for 7 days straight pretty heavy pretty severe. Well when my period was 2 days late I started to worry badly and took a test it was negative (it was the first response test that tells you 6 days before missed period). It was negative I was a bit relived but still worried about why I was late. Today was my 4th day late and I felt nausea in the morning so I had one more test the digital first response so I take it and wait and wait and wait well over 20 minutes its supposed to take 3 minutes and it comes up with a DAMN QUESTION MARK A WASTE OF 20 DOLLARS, so I look at reviews and theyre all terrible It had 1 star so someone says break it open and youll find a regualar strip in there sure enough there was a regular strip with one line meaning negative. So I still feel nausea and I go pee and I wipe and my period had come and it was very very light, witch is weird for me Im always very heavy. Im still not bleeding much. Has this happened to anyone else? Im still concerned about why my period came so late.