Don't forget that you need carbs to replenish yourself post-workout or the protein would be wasted.
Take foods high in dextrose (well any simple sugar) and it should be more than the protein.
I did some calculations and for me (target bodyweight 68kg) I need about 37g protein and 74g carbs post-workout.
So I mix my whey with about 500ml soy milk (high sugar, relatively high protein).
The calculations were based on the 1st post of this thread.

Also, I think you need to get more protein from natural food (in between meals).
I sometimes take tofu or tuna (they add about 24-40g of protein).
HL milk is an awesome source of protein, 50-52g per liter.

Personally I'm only take whey post-workout and on non-workout days all my protein are from natural food unless I can't meet the quota lol.