markie, i'm not trying to be rude, or unsympathetic, but from your description of your original injury and its long-term physical effects, i question your ability to handle the physical demands of nursing. you even go so far as to mention your open disability case, which implies a physical condition that keeps you from working at full capacity.
patient care requires a lot of carrying, lifting, pushing, and pulling, with each and every shift. for instance, are you capable of repeatedly lifting 200- to 300-lb patients, or of dealing with an out-of-control patient during a psychotic episode? yes, there are some jobs in nursing that do not involve direct patient care, but they may not be available in your area and, typically, they are not open to new nursing grads.
i'm not trying to discourage you, but you need to give this some thought.
i do recognize that you feel like you are backed up against a brick wall right about now. but you do not choose to enter a career because you want to freeze your existing school debt. from your description, your loans are already at unmanageable repayment levels. have you actually sat down and figured out what salary you would have to earn to pay back existing loan obligations? you need to do this before accumulating any more student debt. i'm sure that you know that, unlike credit card or mortgage debt, student loan debt cannot be discharged, even by filing bankruptcy.
markie, i can remember being 22, and feeling desperate about where i wasn't in my life. i'm glad that you are concerned, because so many people your age aren't these days, but you are definitely not too old at age 22. you'll benefit from your experiences and your maturity. if you go to your local community college, you'll be astounded by the variety of students: ages, backgrounds, academic achievement, experience, goals. be open to meeting and conversing with your fellow students - of all ages. it enhances your educational experience, and you can make valuable contacts for your future.
successful people make learning a lifelong goal. and note that i am saying "learning", not "formal education". just because you don't have money, doesn't mean you should use it as an excuse to stop learning.
you need to go to the community college and speak with the counselors. you should see a general ed counselor about your educational and career goals. write up a short description of what and where you have studied since high school), and get copies of all your transcripts and take them with you. you should also see someone in the health professions/nursing dept. about what is involved in being a nurse, and the required courses.
as for being "dumb", i don't know you and cannot assess your intellectual capacity or academic abilities. but i will say that most of the students i have met in my life who claim to be "dumb" because of a record of ds and fs on report cards have, in reality, simply not studied to the level required by the class material.
and, yes, nursing requires extensive education in the biological and physical sciences, and in mathematics. the material is difficult. you need to approach your pre-nursing studies with this mindset so that you are mentally prepared, and you need to consciously set aside the full amount of time the instructor recommends for study, and use it for that purpose.
don't be afraid to reveal that you do not know or understand something. if you insist on "faking" competence in a class, how will you ever learn anything? (it's not like the teacher can read your mind). believe me when i tell you that most times you'll be the class hero because half of the class has the same question. ignore the blowhards who brag about how easy a&p was, or that they breezed through microbiology; they can only deter you from your goal.
and don't try to shortcut. i know you feel pressured by time, but you need to get very good grades in your prerequisite courses to be accepted in nursing school, and you'll need to know the material taught in those courses to stay in nursing school. take only as many courses as you can realistically handle each term (earning as in two courses is better than taking 5 classes and getting 2 ds and 3 cs), and take prerequisite courses for your prereqs if you lack the proper background, or have difficulty with a particular subject.
good luck, markie. i admire the way that you've faced up to your errors, and your desire to get things right this time. just take your time, plan carefully, and, above all, don't waste time and energy looking for the "easy way". if you go into nursing, it will be many years of hard work and complete dedication to your studies. only you know if you the capacity to accomplish this.