Have u ever had a period that was super light?

and I mean. really. light. Like, I'm confused as to whether or not this is my period or not? It's happened before, usually a day or some days after sex, I'll get my "period" but it's so light (doesn't really "leak"/come out if u know what I mean, only comes out a little and when I go toilet). Is this bad?? Some months my period is completely normal and I have a normal flow. But some months it's just... like spotting.