Having trouble figuring out when I would ovulate

Kirstie • Sat, Sep 22 • Married 03/16/17 Mommy to a boy 10/09/17 expecting number two 08/11/19

My cycles are quite weird! I thought they were 28 daysbut they are anywhere between 29-33 days...how do I determine ovulation without strips and temping? Picture of the list view of my periods since the birth of my son last October!