When should I test?

Vanessa
My cycles have been irregular for over a year since I stopped taking the pill. Me and my husband are only using the withdrawal method because we wouldn't mind getting pregnant but also are not intentionally trying yet. 
The last 3 months I've been regular with 31 day cycles. According to Glow, I was supposed to get my period 2 days ago and still nothing. I took a test last week as I thought there was a higher chance I would be pregnant this month and it was negative. Was it too early to test or am I just late? I'll test again tomorrow and I have a doctors appointment next week but I was wondering what you guys thought?
 Would my body randomly go back to being irregular again or could I be pregnant? I've had zero symptoms.
Thanks!