Personally I think your issue is more your connecting pieces and that they are patterned. The value is an issue but the pattern is too. I've only done one GFG and I used a white on white as connectors. My Elongated Hexagons that I am working on now has connectors that are blue chambray. Neither are quite solid, but neither have popping patterns either.
Just my opinion. If you want to keep that connecting pattern fabric, then I would keep darks on the outside petals.
(and yes, it is hard to find a good connecting pattern fabric)