Trying for a baby...12 days late!

Hello everyone, so I'm trying for a baby and have been doing for 2 months now. I had sex all through my fertile window... my fertile window has came more forward to this month don't know why as the green dots was actually on last month before... I'm 12 days late on my period, no sign of period at all.. my boobs hurt, got some cramps in belly, going off food, feeling sick so much but not actually being sick I just don't know what to do or think as I've taken a pregnancy test 2 days ago and it came up as a BFN!!! Whats people's thoughts?! I'm never this late!