WOAH - washing most whites at 90 will destroy them!
They include bras etc, which are certainly not designed to wash at 90.
You do NOT need to wash any clothes at 60, really, modern washing powders are designed to work best at 40.
The only thing that might need hotter is towels or sheets, and really nothing need washing at 90. Only 100% pure cotton can be washed at that temp anyway.
I would say that your key probelm, is bunging it all in together.
You need
whites,
colours
darks (black/navy blue and jeans)
I only use the quick wash setting which takes an hour, and everything comes out clean. But there does seem to be a differnce when it is 30 degrees, doesn't quite sem to shift it.
as to powder
sorry, but I think your persil may be part of the probelm.
It is likely (according to dermatologists) that it is the perfume in the bio making your skin itch rather than the bio.
I di use a different powder for colours and whites, I use a colour specific powder for colours and darks (supermarket own brand) and a bio powder for white.
I think it is hard to get white clean and bright without a bio powder. You could do them once a month in bio, and then put them through a re rinse to get the powder out?
Also, if you use fabric conditioner, that may be causing the itch