what am I doing wrong?

Je
Period showed up this morning...a day late  😞 I don't understand. Oh well. This is what my month looked like. Granted I've only been tryingfor three   months. I'm still learning about all this ovulation stuff and tracking it. I have a 13 year old. Didn't know I was pregnant with her until I was almost three  months along bc I got my period for two months while pregnant.  What could I be doing wrong? Any suggestions?