My mom keeps thinking?

So I started this EMT course to make money while in college (here in the county, they hire EMT-Bs as first responders and they make decent money and they work around your schedules). I kinda like it but I want to join the military, my mom knows this and says she supports me and wants me to join. I still have about 50 pounds till im in the bodyfat standards . But tonight when registering up for classes, she keeps telling me I would like the nursing program. I told her I might not like the medical field in a couple years (I also am looking at the political science/international relations program) and then getting my masters in International relations then working in DC with the government (hopefully with the CIA, DOD, NSA, something like that) (after the military of course, thinking of going into Subs or Intel). She said that the medical field is better because I can make alot of money. Money is nice but I want a job that I like and I dont think she sees that. I told her that I would rather have a job that I like and doesnt pay well over a job that pays well but I dont like. She yelled at me and screamed. How can I tell my mom I dont know If I want to do the medical field as a career (like I said, I like the EMT course and all I learn, I would like to do it for a bit, but I just dont know if its what I want to do for a ca