^ This. Turbine clearly decided that Rogues should remain a flimsy class, with DPS potential that is similar to Paladin, Barbarian, and Bard but with inferior survivability (in this case through both lower defenses and bad combat self-healing). Think of Rogue as a class to pick if you want to raise your personal challenge level in the game. If you want an easy time, play one of the "big 3", although they might not meet your goals; Swashbuckler Bard makes a really good trapper but is not compatible with quarterstaves, and Paladin and Barbarian are both superior choices for staff-based DPS (with a Rogue splash for key enhancements) but have more trouble with trapping (Paladin through insufficient skill points; Barbarian because you can't use trapping skills while Raged).
Rogue does have a couple decent defensive cooldowns. One is the Acrobat also get the tier 5 Spinning Staff Wall clickie which grants 50 PRR for 20 seconds out of every 90; this gives you similar physical damage mitigation during its duration to what you would have if you had Heavy Armor on (adding ~25-33% more reduction). Another is that all Rogues get the
Improved Uncanny Dodge clickie at level 8 which gives you a temporary big Dodge and Reflex Save boost. Judicious use of your cooldown abilities plus Sweeping Strikes (in content where your DC is sufficient for it to land) should help with your survivability.
On a staff build you will want to consider the
Rogue special feat called
Defensive Roll, along with the Acrobat enhancement Improved Defensive Roll (tier 4). It's unreliable but it gives you your Reflex Save as a % chance to take half damage on any hit when your HP are below a threshold; fully specialized with Improved, that threshold is half your HP total. Unfortunately Rogues are a bit low on the HP side so by the time it kicks in you are probably in serious trouble, but it can save you sometimes. At endgame you should be able to push your Reflex Save above 60 without too much trouble, at which point it may not be reliable but it will trigger a lot.
Try to get a Blur item, as the 20% chance to be missed affects most enemies and helps a lot. Technically you will eventually be able to UMD Displacement scrolls (50% chance to be missed), but the scroll buff doesn't last long (36 seconds maybe?) so that's not something you'll do constantly just because it's so inconvenient. Elves can take their racial Dragonmark feat and develop it into a longer term Displacement clickie ability, but that takes a feat and enhancement investment that may be hard to afford, and it seems like you don't want to use a DM.
That reminds me of another advantage of being Rogue 18 is you get to pick 3 of the class special abilities (they are granted at 10, 13, 16, and 19) so you can get all of Defensive Roll, Improved Evasion (reduces magic damage you take), and Opportunist (increases DPS). A Rogue 12 only gets 1. OTOH 16/3/1 will get 2 picks and Defensive Stance and be a bit less squishy, if you prefer that to the big DPS boost at Rogue 18.