If you up lvl go Ret you can go pull 6 mob easy kill all and finish full life lol
For second spec go Prot because nobody play tank and if you want dongueon for quest you can make a group easy
Since you are still leveling and you don't really need second specialization, just keep going as retri until you hit lvl 80. After that you can find what you really wanna do, PvP or PvE both are interesting in thier way. If you find retri that interesting then go with retri PvE as MS and retri PvP as OS. Protection PvP is fun also, atleast for me, but best thing is that you decide what you wanna do by yourself.