How long for a ➕ ???

I'm currently 4 days late.  I've had AF cramps and lower back ache for the last 8 days and had no spotting at all, I do think that I'm pregnant this time due to other symptoms and pains if had around the time that would have been implantation. I've taken a test with fmu and its negative?! Did it take anyone else a while to get a positive? I'm never more than 1 day late and I feel very wet down there so keep checking and there's just watery fischarge (sorry tmi!)