Thought I was starting my period?

So I'm three days late according to Glow, which I know isn't always 100% accurate. This afternoon on my lunch break I used the restroom and was excited that I finally started. When I got home from work, there wasn't very much on my tampon. It was more than spotting, but not enough for a period, especially on the first day! I'm normally heavy the first two days. Does this happen to anyone else? I'm happily married with a 19 month old so if by chance I am pregnant, I wouldn't be upset at all! But I have no symptoms of pregnancy. I had very sore and swollen breasts when I was pregnant with my daughter. Anyone have ideas?