I think the key fits your voice quite well, so I wouldn't worry about it, the vocals and harmonies sound good.
The drums are mellow and relaxed (the opposite of what I normally do grin ), but your song (minus the guitar solo) is mellow and relaxed, so the drums fit the song well too, and it's all about the song, not the individual elements of it.

What I would change is the guitar solo, it's too hectic for an otherwise laid back song.
I think something slower with more sustain (similar to Dire Straits/Mark Knopfler in the slower songs) would support the song better.

But all in all, it's a good song that's worth keeping. If you're tired from working on it, give it a rest for a few days.
Distance helps when you're stuck.