If you want pure size then you have to eat more. You can't gain muscle if you are not eating enough. I get it though, you want to gain size while not having your waist increase. To do all that, best to always cut down first. You will hate looking smaller but if you cut down to a low body fat first and then add muscle it is easier. I am not saying to change everything up but that is just the advice I give when this typically comes up.