ok ladies I don't know what's going On here , my period started Feb 15th and ended on Feb 18th my calendar said my…

ok ladies I don't know what's going On here , my period started Feb 15th and ended on Feb 18th my calendar said my fertile days started on the 24th and that I ovulate on feb 29 , I had no idea I was already fertile this fast until yesterday . why would I ovulate on day 11 though I thought it was 12 to 14 days u ovulate , can I ovulate early or is my calendar wrong ?