You only really need to have equipment that matches the level of the quests you are doing, not your actual level.

If you're doing your scholar job quests you'll probably want better equipment for that, or if you attempt the Lv35 optional dungeon 'The Sunken Temple of Qarn' at this point (the quest should be available now from Vesper Bay, and the MSQ takes you to that area around Lv25).

And yes, it's quite possible to level a class entirely through doing MSQ + all the sidequests (and maybe dungeons as the story calls for it). If you're running roulettes on top of that, you can easily get overleveled.