http://nutritionaustralia.org/national/resource/healthy-eating-pyramidDon't know where you were at prior to diagnosis to give you any advice except to say look at the food pyramid. When I was at school, a long time ago, this was drilled into us and that is how we live, most days we eat something from each food group so we have a good balance. My Mum was always saying you eat what I give you, and she was big on veggies and fruit and drink water. Saturday night was our treat night where we could have a couple of chocolate biscuits and a cola drink! Sunday lunch was always a roast followed by apple pie or crumble or something similar!
At the end of the day it is about moderation
Did you grab some of the apples that were in the crates at the MCG - gorgeous, so fresh and crunchy!
For me, when I was first diagnosed I was told you are in the typical age group and it was my hormones, no mention was made nor questions asked but what I did or do eat and nor did Breastscreen ask if my Mother used Tupperware when we were kids or in fact if I do!
Hope that helps and you get inspiration from others
Take care