Ovulation test question

Hi everyone. This is my first time using ovulation tests and I got a positive yesterday and I thought, ok il wait a few hours later and see if its darker. It wasn't 😒

So I re tested today twice and both are super faint.

I see some women have their positives for hours but I got mine and then it went.

Is this normal? I know I ovulated last night as I had bad pains and I've had awful back ache all day (I get quite bad ovulation pains.)

Any advice would be greatful. Thank you in advance