Yes, a couple of the traps at that level start to get brutal. STK3, as you mention, and Redfang poison traps, and the blade traps in Catacombs come to mind.
However, it is not true that it's hard to hit DCs for trap boxes. The overwhelming majority of traps can be disarmed with one arti or rogue level and level-appropriate gear (search/disable, intelligence item, +4/5 tools, good luck, [greater] heroism; spot gear if you don't know where the traps are). You may have to sacrifice build points into intelligence to do this though... and on a first-life/new-player sorcerer this might not be feasible. Since you are just level 5, you could consider restarting as a wizard/rogue instead--lots of skill points for spot/trapping skills, and high intelligence with evasion and insightful reflexes will really help with your survivability. Lots of new players don't like the idea of restarting, but honestly, everyone screws up their first character, and five levels is an absolutely tiny investment in the large scheme of things.
I started a
tip thread for trap bypassing/damage mitigation in no-trapper parties last week. Are you playing on elite? As a first-life character who doesn't know the quests, I would advise running on normal or hard, where trap damage is much more forgiving. Avoidance techniques rely heavily on quest knowledge, and if you don't know a trap is coming up, you're 90% of the way to dead already. Most traps in DDO are static: always in the same place. Running through a dungeon once will teach you where they are