You can work during grad school. At least, a little bit. A lot of students work weekend option, which is working 40 hours between 3 p.m. Friday and 11:59 p.m. Sunday. Hard but lots of people do it. Or just work 2 or 3 regular shifts and have spending money.
You could maybe live with your parents and not have to pay rent and utilities. I know rapid transit is pretty non-existent in southern Cal so you probably do still need a car and gas money, insurance, and parking money, car maintenance. Eat cheaper by cooking instead of eating out. Eat peanut butter and other inexpensive but healthy stuff. Borrow textbooks or buy them used online instead of new at college. Have your family give you a decent stethoscope for Christmas. You need a middle of the line one, not the ultimate in Cardiology stethoscopes, unless you know you want to go into Cardiology. Have them also gift you some school supplies and/or scrubs
and some work shoes.
$28,000 + $14,000 = $42,000. Where do get the $90-200,000 figures?
You'll do ok. Just check out these suggestions. Maybe you could also make some money by selling stuff to the other students. Food always sells. Or type their papers. Or sew for them.
Try to work off your BSN by getting your employer to pay for it. You receive loan forgiveness when you hire on and commit to working for an employer for a certain term. This is very common. I wonder why no one informed you of this.