I wasn't sure if I should laugh, or give XP. But this is the truth.
The issue that the OP has isn't with the class, it's with short rests. And it's the same issue any class that is short-rest based will have.
If your campaign doesn't use short rests (for any reason) all short rest classes will seem underpowered.
The solution isn't to buff those classes- it's to change the timing (even if it's to make it more hardcore, as in turn all long rests into short rests, and a long rest is 1/week or something!).
Or, just play a sorcerer or wizard and don't worry about it. Import the fluff from the warlock.
My post deserve more a laugh than xp.
But I also think that the solution is in the encounter size, number and pace.
Dm need to leave the autopilot, and setup various work day.