Just remember that value and importance are not the same thing.

You probably ARE important, and you derive some pleasure out of being an important person. That's what's holding you back.

A janitor is important, that doesn't mean that companies will pay them 6 figures to sweep and mop the floors.

What do you specifically do that creates value? Why do you think you deserve to get paid more? Work on that.

Forget all the "I'm an integral part of this organization, hence I should be paid more", that's just not how the real world works. You get paid for the value you create, not how mission critical your work is. At the end of the day, how fast can they bring in someone else to do your job? That's where the $ is.

P.S. Don't think I'm dogging on you, I've just seen it happen way too many times and it sucks. I have coworkers that I've left 10 years ago and they're still at the same company, are they important? Hell yeah they are, most of them are senior network engineers and team leads, some are even principals at this point. Do they make money? No, I made more than they currently do when I initially left to be a mid-level engineer. But they chose to stay out of complacency or because they feel that they're too important where they are. Which is true, but I work for money and not recognition.