NTA because NOBODY (or almost nobody) around you has the faintest idea what you're experiencing.
I want to give you some advice-- advice that comes from extremely similar experience.
What you are experiencing in terms of homesickness gets less painful over time. In my experience, most of us move on from the "I hate it here" phase after about 6 months. Could be longer for you because you're in a small town in the south (ouch!). There's no expiry date on it though. 6 months is an average. I know that is cold comfort, but I'm telling you this because you'll go through several stages. The first is just the fucking worst.
Make friends /acquaintances with other people who are not from the US or, if there's a shortage of those, people whose parents aren't from the US. Most people who've moved to the country from abroad will be sympathetic and always a good laugh when you just need to rip the piss out of the host (US) culture and people. Seriously, meeting people who've had a similar experience will bring you more relief than you can imagine!
Correct adults about their misconceptions about Ireland (and anything else that you know better) because they should know better. Many don’t. They’ll probably not appreciate it but they don’t appreciate you anyway.
Get to understand the American educational system— especially the bit about getting into university—quickly. The system in the US is different. There’re lots of things here that are meaningless to non-Americans but which become important for university admissions. Also, just the way classes are graded and students are assessed is very different. If Ireland is anything like England in this respect, two things that are incomprehensibly important in the US are things like behavior and timeliness. I’ve seen kids from abroad have their educations derailed because their homework was late. FFS!
The biggest risk for people like us is falling in with druggies. Try to not do that!
Aaanyway, as you can imagine, I’ve been through the same type of ordeal, but the other way round. And many other ways around. If you want to reach out, I’d be happy to help.