If you applied to 50 jobs and you heard back from 4, something is probably wrong with your resume. try reworking that.
If you wanna stay how you've been (working for ad agencies) fire up google maps or whatever, and run some searches - send some emails, try to call people, etc...
You obviously got jobs before with agencies; find some new ones.
I'm on the fence with degrees - some fields require them obviously (doctor, dentist, etc...) some do not (mechanic, web development, etc...)
I never regret not getting a degree - its made me who I am and I fight for my self education / jobs I apply for. But its never been "easy" not having a degree.
I think those of us without degrees are more "hungry" then the rest. Because we didn't sit in a class and were feed knowledge and had to go out and get it ourselves, we seek out new knowledge more than someone with a degree might.
Plus - sitting through 2-4 years of uni won't help you now if you have no money. Fix your resume, maybe do a portfolio website for yourself and find a job. Then, while working, if you still want to get a degree, go get it.