A story requires as many bodies as there are people who need to die.
I've read books with body counts that number easily into the twenties and thirties (no wars, just bad guys getting taken out, run over, shot.) Sometimes the book is good, sometimes not. What's more important is whether the story needs those people to die, or not. I prefer a reason for them to die, and not just because it's fun to write.
Does every one you're killing need to die... as in on page? Or can you move some of it to the implied category (if you're worried about killing too many.) And would everyone who you're killing really die from their wounds?
(And a note on what Ruv Draba said-- do NOT include those backstory words into your story. Stay focused on the tale your telling and don't get sidetracked telling the reader about the dead folks' histories.)