I wouldn't be too hard on yourself. Cooking regular food is pretty tricky business. Cooking low carb almost requires a degree in rocket science. This is cutting edge stuff here. Give yourself plenty of slack

As far as your whey powder questions are concerned, I think the brand you are using is perfectly fine for baking. There are slight variations between different brands (different sweeteners/carb contents) but the brand you have seems to be the norm. And the age of the powder shouldn't effect the texture of your final product.

Kywoman's suggestions are on the money regarding your pancakes. The one thing I would add to this list is trying more whey (1 more T.?). If that doesn't give you better results, then try increasing the baking powder. If you are still not getting what you want, then delve into the more complicated stuff like beating egg whites and gluten.