As a licensed stylist with over 18 years of experience, Brassy tones are the shades that reflect orange copper...It use to be no one liked brassy tones. From your photo above you look pretty blonde to me.
A past trend was carmelizing hair with 3 shades...brownish, blonde and yellow gold.
If you like the color and your friends thinks it is cool just leave it.
I am surprised she did not suggest just putting a toner on you to take down what she saw as brassy. good luck!