Lighter test with fmu then darker again??

Did this happen to anyone else?

I’m not really sure what dpo I am but think I would be due for my period tomorrow so possibly 13dpo, but really have no idea as my cycles have been different and my lh testing this month was way off.

First test was yesterday lunch time. Two middle ones are in the same urine this morning with FMU.

Last one is today lunch time (4 hours after middle ones) and I only had a coffee in the mean time.

Why are my FMU ones fainter? I thought they would be more concentrated. I noted in my last pregnancy a few years ago my morning ones were always lighter than the day before. Why does this happen? I was starting to stress I was having a chemical. I see a Dr in a few days to have bloods..