Hi Steve,
Stick at it, I did a WW2 para Arnhem and I know how how frustrating it can be. I did find some good advice on here. I had a good reference picture that I followed, a great paint mix that was posted on here. The other tip I picked up to unify and tone down the camo was to spray (at a low pressure) the Dennison with very, very thin diluted black coats, letting thoroughly dry between each until you achieve the desired effect. Don't forget to add your X21.
Another tip I picked up for the weathering was get some kids chalks from the pound shop. Grind them down to a fine dust add your paint to simulate the effect you want, I chose brick dust for mine.
Hope this gives you some food for thought mate.
cheers
Richie