If I were on a calorie deficit I would have lost my belly time ago.
Horazio, independent of eating at a caloric excess or a caloric deficit, you can eat in a way that causes you to lose muscle and hold onto or add to stored body fat (the opposite of what you want, right?)
You would benefit from bulking and from a bit more precision in your diet. The reason I say “precision” is that if you get sufficient protein and good fat and learn how to manage insulin to your benefit, you can do the opposite of what I alluded to above.
While bulking, you could put on max LBM (Lean Body mass, aka “muscle”) and a lesser amount of fat. It’s called body comp manipulation. John Berardi has written on it extensively. If you have the time and are really motivated, I’d recommend you read everything here on the site that he’s ever written. Just do a search.
Oh, and one last thing, you don’t have to worry about protein damaging your kidneys or anything else. That’s just one of those urban myths. The only people who have to watch their protein intake are people with end-stage kidney disease/failure.
And if they (or you) were really in that state, they’d be in a hospital and the doctors and nurses would be watching their protein intake! (grin)
So back to your original question, if your protein intake is low (less than 1g per pound of body weight), then yes, consuming more whey on a daily basis would be a very good thing to do.