yeah but you had a job which gave you access to free food and you didn't count your lift tickets in there.
plus, summer is different from winter. I say get the season pass, because if you're there for three months, buying small deals (i.e. 6-day pass) will be more expensive in the end, and you won't want to spend your tickets on days that are not 100% perfect. When you have your season pass, you can go anytime, and if the conditions are not good, you just get back home and your money is not wasted.
concerning food, that's up to you I think. You can eat cheap in Whistler, but you'll get the quality of food that goes with it. Eating good WILL cost a lot of money.
Honestly, I prepared a budget for this summer before leaving for Whistler, and spent about twice as much as I expected, so take that in consideration. You can't predict everything you're going to do once you're there, so plan a more than your basic needs (food lift tickets ans booze).