Hi there,
(I really must change my username as DS is nearly 2 now!).
I can't give you a definitive answer, I'm afraid, but it does sound a bit like implantation bleeding and similar to something I've had the last couple of days. It's also possible it could be your period coming early though, so I don't want to get your hopes up.
I didn't think that my period was due until Fri or Sat at the earliest, but it seemed to start early on Monday morning. I'm usually fairly regular and have been off the pill for 3 months now, although this is our first month ttc. I did have implantation bleeding with DS though and it was only a tiny bit of blood a couple of mornings when I wiped (sorry if tmi).
This time, it started as if it was a real period, but never got heavier and I didn't need to put a tampon in. It has all but finished now so it only lasted 2 days really. And, yes, it did seem kind of gloopy (sorry again if tmi). So now it is a waiting game.
If I were you, I'd wait until you thought you were supposed to have AF before testing, as if it is implantation bleeding I think it takes a few days for the levels of hormones to rise sufficiently to show up on a test. I think we may be in the same boat however!