Getting the carbonation right can be a bit tricky. Since you used all of the materials, it is probably very close to the intended results. Darker beers don't necessarily have more body than lighter beers. They should have roasty/toasty/coffee-like flavors.
Remember one unassailable statistic, as explained by the late, great George Carlin: "Just think of how stupid the average person is, and then realize half of them are even stupider!"
"I would like to die on Mars, just not on impact." Elon Musk