Early period or something else?

Heather
So my periods have always been regular at every 28 days. It might come a day early or a day late. Well, it was supposed to come this Sunday the 16th but I started pink spotting only when I wiped late Wednesday (12th) evening. Woke up Thursday (13th), nothing. I got to work about 2 hours later & I started bleeding. Put a tampon in and I bled, but not much. Fast forward to today. I'm expecting my period to actually start and get heavier. But no- I changed my tampon and there was next to nothing on it. I feel like next time I change it there'll be nothing on it lol.  I'm so confused. My periods aren't normally like this. Anyone experience something like this? Hubby and I are trying to conceive.