super light bleeding day AF due?!? help!

Alicia
Husband and I are TTC. AF (I think) showed up 2 days later than my usual cycle. 
It's been very light, with mostly brown and pinkish red. There has been some red blood, but not more than a quarter sized amount each day. 
Day 1 and 2 were light, not enough to fill a light tampon for the whole day and day 3 (today) has been basically spotting. Still a mixture of brown and some pinkish red. 
My normal periods are light/regular the first day and heavy the next 1/2 days, then back to regular/light for the last 3 or so.  
I'm so confused! Is this AF or could I still be possibly pregnant???