Dunno how the medic stuff works but we always need a medic in a group. Medics need to stay near the groups but away from battle unless needed.
Remember that's it's not about how many kills you get, it's about how many deaths. If you're getting a lot of kills but a lot of deaths too, that's bad.
Someone who goes 12 and 6 is doing better than someone who is 20 and 18.
So keep your deaths down and slowly get your kills up. Play smart, be patient.
Also, if you don't ever zoom (which you shouldn't because it's awful on this game), switch the zoom to hold, not toggle. That was fucking me up last night.