The picture is great even if the focus is not 100% perfect. Fantastic lovely pastel colors in the background and a very pleasant perspective.
Jack already gave you already some really good tips.
The shutter speed should be around 1/250s or at least 1/160s for a free hand stack.
In your case it's caused by the wind which is really tricky. You can try to use a higher shutter speed with an underexposed picture. -1 EV should cause no problems and give you probably a higher shutter speed. You can correct the exposure later on in PS or LR. Apart from that try to find a way to fixate the flower or the leaf somehow to reduce the shaking.
I have to test focus stacking with a flash and cannot give you any tips about it.