Could Delayed Periods Be Due To Hormonal Changes?

This month I doubled up a couple of times on Junel Fe (don t remember how many times or when) but me and my husband have unprotected sex and I am 8 days late on my period, I had unprotected sex during the week I was supposed to get my period. I took 4 pregnancy tests and all came out negative. Is it possible that I am pregnant or my hormones are thrown off because of the doubling up? I have been feeling symptoms like I am pregnant but I am unsure.