Well, I feel pretty certain that even though every little bit of extra food you eat may not turn to muscle, I do believe that most of it will get used up metabolically since lifting weights raises your metabolism for a while after you're done. So, even if you're not gaining muscle, I don't think you're gaining fat either, unless you ate like 4kcals every day!
Ohh, and on the green tea matcha powder -- I LOVE that stuff! Whenever I have it (I just ran out the other day, boo) I can pretty much put it in everything: coffee for lattes, almond milk for chai tea, smoothies, lemon juice + pellegrino (green tea soda! ha) and I've even baked with it before. It's supposed to be really good for you, too, since you're consuming the whole leaf instead of just the steeped bits from the plant. I think the next time I pick up some matcha, I'm going to try making green tea flavored gummy candy with gelatin! haha, I love making weird stuff.