with a kdr of 3-4 you wont go up in rankings mate, dominations and godlike points and captures are the big hitters, I had once around 200 dominations 1.700 kills with a kdr of 10.00, just went up 2200 points, if you want to go up, be a medic and leech from a good heavy, 3 points for each assist, and 5 for each uber, and the dominations will be fast since you dont get killed a lot standing behind that heavy, I remember when Slaazz healed me he went up 2000 points in like 1 hour.
Also the annoying part of dominations is that if the player get a revenge, you actually lose points as well (2 to be exact, which I think shouldnt be but I wont argue about it) and if you get dominated you will lose 5 points. if you want to be very cheap (which I dont do actually, is to switch teams if you dominated 12-14 people, that way the dominations are cleared, you can dominate them again and you wont lose points for that revenge, but if you do that you are really trying xD)