worried/confused

I recently went on vacation for a week with my boyfriend. We had sex everyday pretty much.(first time in YEARS) All unprotected and I'm not on birth control. I ovulated on the 14 of march. But we didn't do anything until the 16-23 of march. My period was supposed to start March 28. I started spotting March 29. It lasted off and on for 4 days. Maybe an ounce in total of what has come out. It's usually 3+oz a day during my period. My period is usually very heavy. Like "release the dam" heavy. I've taken a total of 6 pregnancy test and they all come back negative. Could the traveling, new diet(I have an iron deficiency), and new "activity" maybe cause all of this?