Graduated with 64k in debt, that's after parents paying for 25k and half covered by scholarship. Worked 20 hours a week part time through school, got a shit job right out of school, was able to hop to a good one, and paid of my debt in 3 years and did a lot for my CV research wise. I worked my ass off.
I'm lucky in my genetics (parents with a phd and a masters), and I'm lucky I met certain people with certain connections, and I'm lucky to come from an upper-middle class household which encouraged independent thought. I'm lucky I was put in circumstances which required me to develop a work ethic.
People who work their asses off and are intelligent tend to be luckier, and that's not a coincidence. People make their own luck often enough.
OP, good luck with that debt. If moving in with your parents is a possibility, I'd do that and get it to a manageable level. I would not take on more debt. There are some PhD programs out there that'll give you 30k+ as a stipend, but unless you've managed to publish, those will be a reach. I also wouldn't pursue a PhD unless you are really sure you are academically inclined (as in, you want to teach and research for the rest of your life), in which case just make sure you get into a program that offers you a tuition waiver...any program lacking the funding to waive their tuition is not a program you want to attend.
As far as MBAs, CC is right. Your sister might have awesome GMAT scores and got a rec letter from a well connected prof or just got lucky. But I wouldn't count gamble on that happening a second time. For the top MBA programs, work experience is all but a requirement (there are some exceptions). If you really want to get an MBA, I'd look at it as a long term project. Don't plan on attending a program in the next two years...instead work on making yourself the kind of candidate that the program of your choice would want. Attempt to find work abroad...I think that's the biggest thing.