Cervical mucus and negative First Response Pregnancy Test?

okay so me and my husband used condoms and he didn't *** in me...now we know there is still a small risk of pregnancy from pre-*** so we're not dull on the subject but...I have had times where I missed a period for 2 months and wasn't pregnant..I definatly do not have a normal schedule from time to time...but this time..i was due around the 7th of February...and It's two weeks later and still nothing. I've had an increase in cervical mucus...feels like my periods starting but I go and it's just mucus...I've taken a bunch of pregnancy tests including one two days ago or so...and i made sure it was an early detection one....First Response claims 4 days before your expected period you can test....it's now 2 weeks past the day I should have started...but it's still coming up negative...anyone have any thoughts on this? I don't recall having this much mucus before but if there are enough hormones to do that wouldn't it show up on a pregnancy test finally? I've tested and re-tested...i did two in the past 5 or 6 days.