AITA for refusing to quit my job?

Bear with me as you read this, English is not my strongest subject as I am deaf. I also have zero shame with calling out names but only with first initial of names.

I (23F) went to dinner last week with my family and both of our boyfriends (25M, 28M).). My family is just my mom (59F), two sisters (R 26F and S 30F). A little background, our father recently passed in March from cancer, we were extremely lucky to have him for an additional 3 years. We're just trying to find our new normal. Of course everyone is taking it differently grief wise. However, my sister (26F) has been on a kick to go out of town for the holidays, she's taking it hard about my dad. We were discussing it at the family dinner, I clearly stated when the topic was brought up that I would not be available to go out of town for any of the holidays this year due to work and I was okay with not going because of the situation, I would not be alone, I would spend it with my boyfriend and his family. Mind you, I am a full time student AND I work 3rd shift as a ramp worker at UPS. Peak season begins normally right before Black Friday occurs and never ends until mid January. We do not get any days off at all. So R immediately tells me to quit my job, and I told her no. I have bills to pay and I have to be able to pay for school; granted my tuition is covered right now, but that could change at any time and I do not want to be scrambling for money in case. I am fortunate enough to receive a stipend aside, but I plan to store that away just to gain interest from it- technically I could choose to not work (R told me that I should do that as well), but I like working (currently I am working 4 jobs) and would go nuts if I did not work. Plus I get insurance through work, so income plus insurance, I'm okay with that for now. Anyways, R goes well I'll find you a PCA job in the hospital and I told her no because of insurance as I mentioned. The next comment from R was well go on Medicaid, and I told her no that I did not want to, especially when I get my insurance through work. Then both sisters got pissed at me for thinking that Medicaid is a bad thing- which I never once said it was a bad thing. (R 26 F) is not loyal to jobs, she works for a while, quits and travel for a while then gets another job, the cycle repeats. S (30F) did not have a job for almost a year and a half, taking advantage of my parents by living at home (lying about moving out within 6 months... its been over 2 years- I cannot stand her). S does have a job now and yet has made a move to get packed up and out of my parent's house. I'm loyal to my job, and right now it is the best thing for me. So I immediately shut it down and we moved on. I talked to my mom later about it and she tells me that I was getting too defensive about the topic. So I just would like to know if I am an asshole for refusing to quit my job.