It really isn't that difficult to level up. It all depends on how much you play, how many battles you do and if you do the side quest. With my first wizard, myth, I was a level 47 approaching level 48 by the time I got to DS. That's because I did every possible side quest I could fine, plus helping others in battles and just doing a little farming when I didn't feel like doing my next quest.
I wouldn't rush, once you reach level 50 and defeat Ravenscar and Malistaire, there really isn't much to do except farm and the new dungeon.
leveling up should be easier i mean i'm level 42 and its taken me almost 3 months to level ps: i'm still 42
Lvl 42 is mid- to late-MS if you are doing all the quests. About 10-12 major quests, give or take a few, should level you up (each of the areas in MS should take you up about a level if you do each as the avg is 9-10 levels gained in the world. Approx levles 35-44 is what I normally see with my characters).