This sounds like a bad job and you should find another.

At some point you were happy with $200k and 2%. Now you aren't. I don't think there's a bump that they could give you at this point that would make you want to tolerate the shit that's bad about the job.

Note that this is a bad job. Startups are more prone to creating bad jobs.

The math for employee #1 at a startup is almost never ideal if you're being completely rational about expected value. That is, I think, a separate problem than you're dealing with.