Missed period, sore boobs, feeling sick someone help

Hi I’ve been off the pill for 6 months my periods started up again after 3. I have tried every month having lots of sex especially while ovulation. But I got my period every time. But this month I feel different I have really gone off food and feel sick all the time. I have sore boobs. Really bad mood wings and now I am 6 days late. I did a test on Thursday (the day I was meant to come on) but negative! This might sound stupid but could I be pregnant? Could I taken the test to early? Could the test be wrong? X