Confused

So my husband and I are trying to conceive our first. I’m horrible at figuring out my cycle. We have been trying for 6 months. Course, three months in I found out I have endometriosis. So I had a surgery to remove the endometriosis and that was three months ago. Up until January, my period had been starting the 23rd-25th every month. But out of nowhere in January I started on the 18th. So now I am not sure what is considered “late” for me. Tomorrow is the 18th and I haven’t had any cramps. My breasts are sore. My areolas look so weird. I’m tired. And I was spotting very lightly last night. Haven’t bled anymore. I realize it may just be my period coming but how do I know what is “late” and when to test? Would it be after the 18th? Or do I test closer to the 23rd? This whole ttc thing is so frustrating.