Plays had best become your focus, as they are one of the only opportunities inexperienced folks have. You will also need to try to find ways to work with people, even if they are people you don't like. Not everyone in show biz likes each other, but they rise above it for the good of the production (this is true of business, too, BTW. A big part of maturing is dealing productively with people who piss you off).
I would also suggest you are, more likely, just afraid of choosing a major. So you selected acting. But here's the thing - you don't really need too much of a major to get a two-year degree. So chill out and select something in the general area of things that interest you and you can get good grades in. General courses of study are (I may be missing a few, but these are a lot of 'em):
- Humanities (English, foreign languages, etc.)
- Social Sciences (Philosophy, Political Science, etc.)
- Hard and Soft Sciences (Math, Physics, Geology, etc.)
- Communications (PR, TV/Radio, etc.)
- Medical and Related (Nursing, Physical Therapy, etc.)
- Engineering (Civil, Electrical, etc.)
- Visual Arts (Pottery, Painting, etc.)
- Performing Arts (Acting, Singing, etc.)
Or just go here, and start poking around - https://www.onetonline.org/
Bottom line, you can go fairly generic and don't need to specialize for a while. And here's a dirty little secret - most people get a four-year degree in something or other and what they end up doing for a career only relates tangentially to it, if at all.
Acting might or might not be a good choice for you, but you should have a passion for it. Auditioning is a difficult way to get work, and casting directors will spot someone who is phoning it in a mile away. Because this is such a recent conversion for you in thinking, the truth is, it is going to look like that.
Because people who are passionate about acting have, even at your age, been in productions, have usually taken tap, ballet, or singing lessons, and are committed to working on productions even if the conditions aren't ideal because they see their futures ahead of them and understand they may need to do less than fun things like commercials for acne cream in order to get their SAG-AFTRA cards and put something on their resumes.
Still want to go into acting after all that? Then you need to play catchup. Singing lessons, dance, and summer stock are all in your immediate future if you really want to do this. It is not an easy gig, but the people who enjoy it find it rewarding, even if their grandest achievement is as an understudy on Broadway who goes on exactly twice, or a stunt person.