I am not going to repeat after the others, even though I share their view!
I'm not going to bore you with technical details. I suspect you got into the wrong mindset when mixing/mastering this song. You got into the mindset of making something fast, energetic, pumping. But this song is slower and moodier than that. It wants to breathe, it wants to sound natural, it wants to have the dynamics and timbre of the sounds intact. In fact, I think it wants those long, rich sounds to be the focus - loud, clear, but definitely not squished with compression. Chances are good that I'd use the drums more as color than as anything else, were I you.