Do Not Worry About Your K/D
I have never been one to focus too much on my K/D anyway. But this is especially true for War Mode. It is all about the objectives, so as long as you are actually assisting the team and helping work towards your goals that is all that matters. Your objectives come first and if anyone gets in your way, you take them down! It is not a case where you are actively running around looking for other players to gun down.
The progression in Call Of Duty WW2 is far slower than it has been in previous years. I am not saying it is Star Wars Battlefront II level of slow. But it certainly feels like it takes longer to progress in this game than the last few. I do not know the exact stats, but the rate you earn XP certainly feels like it is much slower than in previous games.