Why am I bleeding a week early on day 23?

Hi, my fiance and I have been trying to conceive for a little over year now. Last month after I thought I was pregnant and how obsessed I was, I decided to not think about it and not try. Well my menstrual cycle is usually days last month I had my period 4 or 5 days sooner. So this app I have on my phone tells me I am now on a 31 day cycle so I should be on the 26th. Today is cycle day 23 for me and I'm not suppose to come on until 8 more days. At first it was only spotting with alot of CM on Toilet paper at about 1 or so in the morning, then about 9 tonight I went to the bathroom and it's pink but more than yesterday and only when I wipe. I do not understand why am I bleeding like this?