I ended up doing this and switching to enlightened spirit and now I'm blasting through legendary content and almost to 30. Trying to bang out enough seeds for two hearts and double incarnate back to 20 then back to 1 and do a sorcerer playthrough and try to do reaper as I'm leveling for some points on the way. Even now certain quests just kinda neuter my character in specific being immune or straight up healing from fire damage. Have to turn off my mantle and pact to slowly poke something down is extremely lame
I feel like that little point around 16 when you don't quite have a real setup yet for enhancements or gear was pretty painful compared to what it feels like now with epic destinies. The big power increase, tankiness, access to healing and temp health etc since quests around that point tend to be long, full of traps, and the mobs are particularly annoying
I missed the chance to let you know that switching over to ES is probably the single easiest move if your having problems with defense, fortunately someone else already pointed it out. Your totally on the right track in that quests get much more difficult around lvl 16, the real break point is the level 18/19 quests. Getting through these can be extremely difficult solo.
On the note of ES WLK, there are few class/builds that glide through the game with minimal investment as a ES WLK. If you were having problems with defense on a WLK, those problems are likely to be much, much worse on a sorc.
If you liked ES WLK, you may enjoy Paladin. Paladin has a nice mixture of offense and defense like ES WLK has and can be rebuilt for more defense or more offense just by changing enhancements. Paladin is a great class for an introduction to melee combat. You probably want to start out with THF so you can deal some aoe damage.
If you want to play something very similar to sorc but that's slightly more forgiving to a lack of knowledge and gear - Stormsinger bard is a great choice. Sorc gets immunity strip at level 20, which means you will be dealing with immunities from lvl 1-19. Sonic damage on the other hand pretty much works on everything to varying degrees, caster bards can also heal themselves quite well. Fascinate is one the easiest CC abilities to get to a working level, and it's quite nice for soloing. Sorc is super popular right now becuase it has a higher ceiling in damage output than most classes, I would not call it a good beginning caster class, although they do have very strong offensive capability.
For the divine classes, they are likely to feel somewhat weak offensively, Druid is probably the exception to this.