Can endometriosis be causing my late period?

So my period is late by 3 days and all I've had so far is a tiny bit of brownish spotting. I didn't get any horrible PMS beforehand like I usually do, but I feel like I'm getting it now on-and-off. I've had bad cramps, bloating, back pain, and today I felt quite nauseated and I usually only get nauseated or throw up on the first/second day of my period. I also noticed the brownish spotting today. I feel like my period is gonna come soon, but today was the 35th day of my cycle and somewhere on here I read you should contact your doctor if your cycle lasts longer than 35 days, but idk why. However, I also know that most of my usual PMS and period symptoms are the same as signs/symptoms of endometriosis, except I don't for sure know if I have it.

Is having a longer cycle another sign of endometriosis? Could endometriosis cause my period to be late and be causing the brownish spotting?