So I'm in a scenario I'm uncomfortable, need some encouragement from fellow devRanters. (Looong post)

I've been working at this startup for about 10mths (since I graduated). They have been really good to me since the start, and overlooked some fuck ups I did at first.

But now I've been way more experienced , picked it up really quick. And I've basically redesigned several of their admin solutions and data products. Also, I'm basically their entire data analysis team now. I do backend (node, PHP, MySQL) and analysis for them (stats, deep learning, python, big data packaging for clients).

But seeing as I've moved in their company, and have been consulted on several major decisions, as well as built a really good relationship with some of their clients. I still haven't seen a raise, moreover I've been told that I'm expected to work from 8am to 5:30pm (9.5hrs no overtime pay). Which really pisses me off, since I know I'm worth more than what I'm paid (about 40k a year).

My brother (who's also a dev) suggested to tell them that I'm not happy at work due to this. And quit if they don't react well.

How should i bring this up? Should I really quit? This is all new grounds.