My manager rejected my overtime pay requested and said it needs prior approval. I didn’t realize I’d work this many hours til after. What can I do?

I know. I’m so stupid for not getting this approved earlier. But I was so tired last week and just started to reflect on it this week. Anyway I worked an additional 6 hours (I worked technically more, but being generous here…) and she’s saying she can’t pay me for it. We had 3 people out, 3 competent people on-deck, and 1 person who is new but doesn’t lift a finger or take initiative on shit. And we had a huge testing process involved for a go-live event. And I was backup on 2 projects and had several meetings within those days.
im absolutely insulted and feel disgusted by my managers disrespect. What should I do?

My manager rejected my overtime pay requested and said it needs prior approval. I didn’t realize I’d work this many hours til after. What can I do?
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