Yes, honestly, the rogue 3/fighter 4/ranger 3/paladin 3 not only doesn't have the right amount of levels (you start at 12th-level, not 13th), but doesn't seem to match up by any stretch of the imagination to the core concept of a pure character of ANY of those classes you've taken. A rogue 12 built and geared for raw damage output would spank that build in every category but hit points. A fighter 12 could reach incredibly high AC and still dish out impressive damage and take hits reliably. A ranger 12 would either soar in melee with powerful two-weapon fighting or waste foes from afar with ranged attacks all while backing up the group with up to 3rd-level spells. The paladin 12 would be a substantial secondary healer with the ability to burst damage on the really tough foes via smite evil while having great saving throws all around and a powerful mount he could summon in the situations where it was viable (there will be a few), not to mention the bolstering against fear and protection from diseases he'd provide. All in all, the multiclass monster you are proposing is a jack of all trades and master of none.