how large does your tumor need to be to have herceptin?

I have a 7mm tumor no vascular invasion, negative sentinnel nodes. Have done 4 rounds of AC, bilateral mastectomy. My onc told me that I should not have Taxol as the risks outweigh the benefits of only 1%. She seems reluctant to give me herceptin as well. On one hand she leads me to believe that I am a high risk of reccurance due to may age, 35, and on the other she says that I am on a lower end. I can't figure it out. Any thoughts ladies?