HELP - late period or implantation?!

My periods normally last 28 days because of BC and recent surgery removing endometriosis, though my ovulation date is not normally the same the last few months - I can physically feel when I'm ovulating though!

I had NO symptoms as far as PMS this cycle (which is odd in itself). Normally I bloat, super sore/swollen bbs, gurgling cramps 1 or 2 days before etc. NOTHING! I did experience very tender nipples from my Ovulation day until the day after my missed period.. I missed my entire 5 day period! I had a VERY tiny dot of pink in my CM (size of a grain of rice) the 5th day around midnight or so when I wiped. The following day I woke up to spotting when I wiped (pink), then while at work the spotting turned into cramps with bright red/pink watery "flow". Again, not normal period blood because usually I experience dark, thick bleeding (sorry, TMI). I bled enough to use ONE pad that day and again the next (usually 2-3 a day), but it was lighter and the cramps subsided. The "flow" turned into light pink scanty spotting, then brown CM. It's now gone, therefore the light bleeding/brown spotting lasted 3 1/2 - 4 days total. I've since felt burning in my bbs and lower backache, but nothing more.

I HAVE NO IDEA WHAT TO THINK!!!! ): opinions?