Goldwell help...

Wanted to know if you could help me pick out the right Goldwell color for me. 

I have light skin with hazel eyes. My natural color is a medium dark brown with about 35% gray.  The perfect color for me is to be  2-3 shades lighter than my natural color (a medium/chocolate brown w/gray coverage). In the past, I was using 7MN with 7NN. This was a med/dark blond color and worked great. As time went on, I was getting more grayer and I found that these colors were not covering the gray well. Then, my hair person reccommended me to go with 6GB. The first time she put the 6GB on my color, it was it was fine. The second time she used 6GB, this resulted in a lot of red in my hair. I don't like red at all (especaill with my light skin tone). The third time she colored my hair, I had her mix half 6GB along with 7NN. The color was a little better but I still saw the red. UGH...  In speaking with another hair professional, I explained my situation. Her recommendation was to use a 7NA (mid ash, ash blonde) on the roots with a 7NA demi on the ends. She said this will cancel out the red and will give me medium brown hair. What are your thoughts on covering the gray along with achieving the right color for me? Thank you for your advice.