Hi.
There's nothing wrong with being undecided about what to do after you graduate. In fact, there are probably a lot more people feeling that way than you think.
It sounds like you have a lot of interests. There's no official time frame for doing things like joining the Army or going to college or even getting married. You can do any or all of these things at different points in your life.
When you move into adulthood, however, the choices you have to make can often be further complicated by your parents' preferences and expectations. Probably the first thing to do is figure out if there are any immediate goals you want to meet over a certain time--say, over the summer or the rest of the year. If you are committed to staying in your hometown to finish your 4-H term, then figure out if you will need to find a job to support yourself and whether or not you will live at home.
There are a ton of different options about college and going into the Army, too. To narrow things down, take some time for yourself to think about what you like to do and research it as much as you can. Try to do this when you aren't stressed about things with your parents--being relaxed about it might help you think of things in ways that you hadn't before. A school guidance counselor or some career or vocational books at a library or bookstore could also help you sort things out.
To get yourself started, you might want to think about how college or the Army would help you pursue your interests. Maybe you can find a way to do both--like serve in the Army so that it can help you defray college costs if you go to school afterwards. Or you can look into military schools. Or, after working for a summer, you might want to take classes at a local college next fall. Or maybe you want to go to college somewhere else.
Knowing what you want to do takes some self-knowledge and insight, but once you figure out some goals, you'll have a better sense of what to do next and how it can make you happiest--even if figuring it all out takes your entire life.