The vet also said that Purina and Iams are a good brand
I don't know why your vet is recommending those brands. Generally any brand you see commercials for on tv are bad and the foods you can find in grocery stores/walmarts.

I feed mine Praire. But I also recomend Royal Canin (sp?) I'll ad more as I think of them I for some reason can't think of anymore.
Look at the ingredients on the back, pretty much anything that starts with actual meat is good.

Your baby is getting so big!