Help!!!!

I have endometriosis and my periods for the most part are regular. Give or take a few days. My thing is because I have endometriosis I’m not really certain when my period begins or ends on the exact date to calculate it. So I’m not really sure when I’m ovulating. When I start taking the ovulation kits so I can try better to pin point what exactly do those mean? Like when you get a smiley face does that mean I should be ovulating within the next two days so I should focus having sex then or what? I’m also going to try pressed this month. My chart says I’m suppose to ovulate New Year’s <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">Eve</a>. I’m just trying to figure all this stuff out...