I think you're doing a brave thing and there's nothing wrong with giving this a shot. You're not being irresponsible by following your dreams - though I can imagine you're probably second-guessing things, and that's natural. A couple years ago I quit my job and traveled the world, without a backup plan or anyone to rely on for financial support. I had to get very creative but I also became extremely resourceful.
You can do this. I'd recommend though that it's important for you to plan on how you can make your own money. Don't put your survival in someone else's hands, you are just going to become more frustrated with your BF and also angry at yourself when things don't go right. You want him to give you $$$$ every week. That is YOUR plan, not his. He doesn't HAVE to give you a dime, and judging by history he might not be all that reliable.
Develop a backup plan. Better yet, view the $$$ from him as a bonus, as opposed to your financial backbone. Can you imagine if he quit his job to freelance, and then said he wanted YOU to give HIM $$$ every week and not be late? What would your feelings be about that? If you maintain control of your own finances throughout, you'll develop a huge sense of freedom and independence along the way, and challenge yourself while shooting for your dreams. You can do it! Good luck!