Is this an indent?

I took this because although I had a proper period, I had random bleeding cd6 and cd7 (after my period had finished) which I usually don’t have. I saw something as soon as I took it! I’m thinking an indent, very confused as I had a very normal period for me!! (Some clots, super tampons) I’m now cd8, and I’m having surgery in two days so I’m very confused!

Obviously I know I can’t be pregnant and have a period so I’m just confused as to why there could be a line there...