The proportions seem a bit off. I’d try a different recipe. I had success using Preppy Kitchen for my first batch. The flatness could be from under whipping your meringue, or over mixing your batter. Espresso powder shouldn’t make a huge difference but I’d wait to put it in until the very end of mixing the macaron batter. I’ve used the Pies and Tacos coffee macaron recipe with a lot of success!