To be completely honest with you OP, why are you dating a 19 year old girl? I know they say age is just a number, but even then, this is lower than the "magic number method" (half your age plus 7 years).
I started dating her because I liked her and she liked me. The age gap is admittedly pretty large, but it hasn't really felt awkward.
The way you describe yourself, you don't sound like you take a lot of responsibility in your life. You're 31 years old and still live at home and depend on your 19 year old girlfriend to support you financially.
I only recently moved back in with my parents because I was running out of options. Up until that point, I've held down a job and had my own place for since I was 19. I graduated college with a bachelor's degree (psychology), but did not have much luck finding good work in that field. The job as a janitor actually a few bucks an hour more than the work I was doing with the psych degree. I've been at that job for five years paying off student loans and trying to figure out what I'm going to do next. I don't want to spend several years on another degree without due diligence.
You aren't willing to stand up for yourself to your step-father and are being coddled by your mother. You're pissing into cans and bottles to avoid going to the bathroom because your stepdad doesn't like it when you walk in front of him? Grow a pair, man. You're putting yourself in this prisoner mindset, go piss in the toilet like a goddamned adult.
I'm admittedly not great with confrontation. My stepfather does not like me, and never has. I know that he isn't a fan of me being there at all, and with it being his house, I figured the less he sees of me the better. I know that it is a pretty spineless strategy.
You have options but are not taking them - you can get into temp agencies and at least have some form of income. Throw away the bottles and cans of pis and piss in the bathroom.
I've applied at the temp agency in town. They've given me a few short gigs, but the work isn't consistent enough to keep up with my bills or move back out. Basically, they'll call me every once in a while to pick up a shift setting up equipment at the local theater or stuffing boxes at the print factory. I'm taking in maybe $400 a month doing that.
I've stopped peeing in bottles and started just scheduling my bathroom time to times where I won't see my stepdad.
You're in no position to be in a relationship right now. Your top priority should be to get out of your parent's house, pay your bills, and take care of yourself. Dragging your 19 year old girlfriend into this and depending on her is extremely unfair, no matter how supportive she may seem.
I know this, and absolutely want to get back on my feet ASAP. I spend most of the day out applying for jobs unless I've got something that day from the temp agency. Unfortunately, I'm not taking in enough to even keep up with my bills.
I do feel guilty about accepting money from her, but she insisted she wanted me to have it. I realize I shouldn't have accepted it.