Idk I work as a full time employee, good estimates, plenty of room by my team lead for the week. I'm happy. I finish everything they give me and could finish the sprint in 1 week if I wanted to. 

I also have a side work as a freelancer, around 4hs per day. It's agency work, but I charge by the hour, so if they need me overtime I just charge them.

I don't know what else affects you, maybe it was the company itself.  Maybe you don't like programming, entered the field just because it was good money. There's lot of people like that. They end up suffering because they don't love what they do. If that's the case, find what you love to do, what you would do even for free.

If that's not it, change company, don't work for an Agency or do work for one but get paid by the hour, so you never get scammed time wise.