The thing is, I'm afraid if I do decide to go to college in Poland, that I won't be able to get a job there and I'll have to go back to the US for work and then I'll have wasted all that time that I could have been going to college in the US.
A very likely scenario. The most probable, in fact, and the one you should base your plans on.
but I have no idea what field I would want to go into.
By your age, you should have at least a general idea. Speak to your guidance counselor. That's what they are paid for. There are good vocational tests that will help you decice.
However, avoid the following: humanities (literature, history, philosophy, etc.), psychology, sociology, teaching (except for science and math), journalism, political science, economics, business, administration, marketing, law and tourism and recreation, UNLESS you are a top student and go to a top school. There is a glut of graduates in these majors and finding work in these fields is difficult because of the competition. A degree from a second or third rate school doesn't mean much on the job market, whether in Poland, the States or anywhere else, especially in these majors.
The more science and math, the better.
Obviously college in Poland is much much cheaper than any college in the US
Nope. You can a great education for very little at state colleges and universities. Berkeley, UCLA and UCSD cost almost nothing for California residents, for example. Even out-of-staters only have to pay for the first year until they establish residency in California. Do your research. Not all of the top schools are expensive private schools.
Also, a degree from a unversity in the States will help you a lot more in Poland than a degree from Poland will help you in the States.
When i think about going to college in the US and being away from my family for that long
Most young people have some difficulty striking out on their own. But most of them survive just fine and become stronger individuals.