I also worked full time throughout college. I averaged 170-180 hours per month working 12's. The first part of my education was done by working 24's, this is much easier because you work so few days per month. Then, I transferred to all night shifts when we went to 12's (traded). This, quite frankly, sucked. Although I am a "night person", I ended up going days on end without sleep (go to school monday, work mon night, school tuesday, work tuesday night, school wednesday...crash wednesday afternoon...), It is much easier early in your academic, and professional, career. When you are just starting to take classes, you have many that you can choose from and can arrange only to take courses that work with your schedule (ie one or two days per week). When you near the end of your degree, you take what courses you need in order to to graduate, whenever they are offered. Likewise, it is difficult if you supervise others or have lots of responsibility with your employer.
Although it all worked out for the best, and I graduated without loans, I am not sure that I would do it the same way again. I loved my job, and always put them first, but I found myself not able to devote 100% to either work or school. They both suffered some.
Consider staying with your current job, working part time if possible, or even taking loans. EMS is exciting, but you need to concentrate on your long term goals.
Whatever you decide, almost any permutation of scheduling is possilbe with enough stamina. Best of luck...