Why is my work making me miserable?

Because at least three different things go by that name, and they call for opposite responses.

The first is structural. You do not own what you make, you do not decide how you make it, and the value you produce leaves without you. On this account your misery is accurate — it is a correct reading of an arrangement, and no amount of adjusting your attitude will fix a thing that is not in your attitude.

The second is a mismatch of expectation. Work was never supposed to carry the whole weight of a good life, and asking it to means it fails at something it was not built for. Here the misery comes from the demand, not the job.

The third is the most uncomfortable, because it does not have anyone else in it. Nobody is making you answer at eleven at night. The pressure is coming from inside, wearing the face of ambition, and you have no one to negotiate with.

These are not three flavours of one complaint. They are rival diagnoses, and the treatment that follows from one is useless under another. Start with whichever sounds most like your week.