Just late ?

So I have irregular periods. I thought my period was supposed to start the 8 and the app Calendar says today . My boobs are bigger they are a little Sensitive when I touch them. But my back and stomach hurt a few days ago like period cramps but no period . Yes, I know I can take a test I'm just a bit affair of the result. Should I wait one more time re week to see if it comes? I've had a little blood not even 24 hours of it.  I also have diarrhea. I'm so confused if this could be pregnancy or period symptoms . Lat time I had sex was 4/22.