Wanting two things that I can't combine in my head

You could do a sort of pillbox hat around an updo. Enough tailoring to go with a suit, bold flowers.
And use varieties of yellow and orange African Daisies or Gerber's for their smaller, compact sunflower like blossoms.

Gerberas, which my spell checker wants to make into other words,

There are more than 20 yellow orange with brown centers, as well as all

kinds of other colors and shapes.

I think some of these styles could easily be worn with your suit. They have flowers and/or flower crowns without appearing too boho.

Here's Shailene Woodley rocking a big colorful flower crown with a suit.

Here's a little more "fashiony" style, and this is a jumpsuit, but similar concept.

And here's a very bright, colorful flower crown with a pantsuit (sorry I couldn't find a picture of her standing up).

I actually think a bright flower crown will look very posh with your suit. It has a whimsical vibe to it, the meshing of these two very distinct styles. And with your suit being white, a bright crown will look very fresh.

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I agree! These are all great examples, and you could go with really large pieces in the back if you don't like how it looks at the front of your face.

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Thank you all for all those pictures, they are literaly ALL fantastic and I really can imagine it better now! I guess I will go with something like the second jumpsuit picture with the bold colours. In fact, that comes pretty close to my dream flower crown and in contrast to so many other haircrown pictures I found on Google, I really see that one with the suit. Thank you so much !

I absolutely agree you can wear a floral crown with that suit! I think it would come across as very fashion-forward and chic! It really is hard to find photos, but I'm sure I've seen some and I think you should totally do it.