I am a level 6 pvp captain. My record is 37-18. BUT, most of my losses have come from level 20s +.
Focus on you rank, your record will sort itself out when you have a lot of matches going.
Sounds like you are a good player and your rank will remain good because when those level 20s beat you they not taking SOO many points as they used to. You can make those points back easy.
you should be playing lvl 20s if your a lvl 6 captain since the pvp rating makes up part of the matching. also there isnt many lvl 6s doing pvp so there are trying to match you up with the closest enemy they can find. which is about a lvl 20.