whey is a milk product, but if it doesn't bother you then that is cool. Must have all the lactose pulled out of it in processing.
You can drink several whey shakes a day instead of weight gainers, but throw in some carbs. Put a bananna or two in there. Even a couple of scoops of sorbet (or a soy ice cream, or something similar that doesn't bother you.....but I would probably only do this once a day) or you could blend in 3/4 of a cup of oatmeal (uncooked) into the mix for cheap, high quality, carbs. When bulking, you can use all the calories you can get.
good luck!