One of the most important characteristics to have in a relationship is empathy. It’s what enables you to understand your partner by putting yourself in their shoes.
Based on your narrative (not included here but the content is referred to in this answer), I understand that you feel entitled to spend your time by doing the things you enjoy, like seeing friends, having a drink, and playing your Xbox, after a long 12-hour day at work. I get that. You work hard. You want to relax and unwind.
Now, I don’t know your girlfriend, or what’s going on in her head, but I can easily imagine she might feel she isn’t much of a priority in your life. Yes, you might be supporting her financially, but it certainly doesn’t sound like you are giving her much time. Maybe you have weekends together, I don’t know. I can imagine she feels neglected, and what you are experiencing as her being controlling, is her feeling like she has no control in the relationship, because work, friends, drinking and your Xbox all seem more important to you, then she does.
This, of course, is all guess work. I don’t know what’s going on but you might consider that she is feeling very insecure in the relationship, and her efforts at controlling you, are her wanting to feel needed, loved and a priority in your life. Just a possibility you might consider exploring with her.
Clearly, after 3 years together, she means a lot to you. I recommend you talk to her about it. Tell her how you feel. Ask her how she feels. Be patient. Try hard not to be defensive, place blame, point fingers, etc. Maybe you two can figure out a better dynamic that works for both of you, instead of what’s currently going on.