The short, blunt answer is you're being taken advantage of and you're letting it happen by being supportive and amenable and working literally a second job lite

The short, blunt answer is you're being taken advantage of and you're letting it happen by being supportive and amenable and working literally a second job literally for free. To be ultra clear I am not blaming you as the victim - people deserve a fair world - but that's the reality of how things are today. Many (not all) people will take everything you let them take and never feel a moment of regret. There are a handful of sad cliches here - the only reward for doing extra work is more work, hr isn't your friend, and you'll never get promoted out of a job you're underpaid for. From your story I think you need to find work at a different company. Your boss knows he has a free developer at his command and isn't going to give that up. I don't know him but if he is as big of an asshole as your story makes him sound like I expect he is the reason your move to the other department fizzled and I would be very wary of him sabotaging your attempts to get a new job. Building software professionally can be fun but it can also feel a lot like this. If you're enjoying the creativity and problem solving part I suggest you start interviewing for entry level coding jobs at different companies. You need to with more senior engineers to set the right boundaries and to help you learn (eventually you'll look back at your first real project and laugh at the bad decisions while marveling that you got it working at all). Use a friend for references not your current boss. The flip side of this abusive relationship is you can probably phone in your work for a while as you recover mentally and find your next job. tl;dr - you have to take action in order to fix this and you probably can't fix this and stay at your current company. You also have problem-solving mindset that will help you find a career that pays much better than answering phones.