CD 36 spotting?

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So I have a super normal period and have for the last 3.5 years. That being said I was diagnosed with PCOS. Because of this I’m not trying but not preventing because I’m in a position where if it happens that’s great but if it doesn’t I’m not rushing. Part of that is because I’m 33 and with PCOS I feel like time isn’t on my side. So my period always arrives on time, always is a 30 day cycle, and always lasts 3-4 days. I’m on cycle day 36 and FINALLY have some very very light light pink spotting I only see when I’m wiping. What could this be? Could it be considered my period or did I miss my period? I took a test after I was 4 days late and it was negative so Ik it’s not that, it just worries me because it’s not normal for me. But am I crazy and could it be pregnancy related?