Eddie, I'm sorry you and your mom are in conflict. I do have some suggestions, but probably not the kind you'd really like to hear. It would probably feel much better to hear about ways to get your mom to change. But we can't change other people, we can only change ourselves.
First, I'd like to compliment you on a few things -- getting through high school without problems, having a weekend job and the nice things you said about your mom as you explained the difficulty of your situation. It does sound as if you're really trying to be fair about the whole thing. You've made a few mistakes in life, as we all have, but you've also done a lot of things right.
Whether your mom is acting fairly or not isn't something I can comment on because I don't know her side of the story. But it's clear that at 18, you're longing for more
freedom and would really like your mom to trust you and give you a little slack.
Unfortunately, it doesn't sound as if she's in much of a mood to budge.
I'm going to suggest you stop fighting her and claim some independence by making your own plans and arrangements. Your father, aunt, uncle and cousins sound as if they support you. If your mom says you can't stay home alone while she's on vacation, you'll feel a lot less stressed if you just accept it and start making arrangements now. Maybe you have some friends where you could stay. Maybe your dad or uncle. Instead of fuming over your mother's stubbornness, go ahead and make your own arrangements, trying to find the place that is most acceptable to you.
I'm suggesting that because I get the sense that if you don't take the bull by the horns yourself, your mother will make arrangements for you, leaving you fuming because your freedom of choice was taken away.
So what I'm saying is this: Grab whatever freedom you can. Making your own arrangements is a good step in the right direction. For many of us, freedom comes in baby steps when we're young. Your mother sounds awfully strict. The more you resist her, the more strict she'll act. It's like you're pushing and pulling against each other, keeping each other stuck. So take action, stop pushing, and claim what freedom you can.
The next thing you're probably really going to hate. I hated it when I was in your shoes, but over time I found it gave me tremendous freedom. Learn your city's transit system and bus routes. Here's a link to Milwaukee Transit (I'm going to guess you're in WI, not OR.)
Milwaukee County Transit System
I have no sense of direction. I get lost inside the grocery store. So, for me, finding transit routes was really scary. But even I figured it out in NYC and Chicago. All of a sudden I could travel all over for a reasonable price. I did get lost a few times in bad parts of town, but nothing bad happened. The important thing is don't panic and make sure you know when the last bus or trains run. You don't want to get stuck somewhere late at night after the buses stop. Trust me on that one.
Grab your freedom, Eddie, wherever you can, starting right now. You're the right age to start making these decisions on your own. Some will be brilliant, others will be blunders, many will just be confusing. But it's how we learn. I wish you the best of good fortune!
P.S. Here's another one I hated at 17 when my older cousin told me to just do it. I did and it worked. I started doing my assigned chores at home early in the day, without complaint and without being asked. I just did it instead of defiantly dragging my feet. Worked wonders on improving my mother's attitude!