I had the same problem at 29 and 39. I always grind some marks to get some PvP-rewards to replace some crappy gear, but I never stayed to long. I often contributed the most by just healing, which made us win, or either stretch the game. Most twinkes I saw were Rogues. I know that, because the only thing I saw a second before I fell dead on the ground were two shining blades. These twinks pick priests for two reasons: 1. We are clothies. 2. We heal players who actually CAN defeat twinks.
Some things that help is to either bubble yourself asap when you see one or use Psychic Scream (of course they will trinket out, but it's damn annoying when it happens to you often). Also SW:P is great; They will not be able to vanish with it on. Ohw, and holy nova is great to avoid stealth-only attacks like ambush.