The above posters have given you great advice, so I want to address two (related) elements that you might not recognize: the self-discipline and time management that formal schooling requires. Neither of these is something that people just have: self-discipline is a muscle that develops over time, and time management is a skill that you can learn.
From your post you have not had much need for either, so most likely these are under-developed. That’s ok! and not too hard to fix, but it is important to recognize that going in. Otherwise, it will catch you off guard, when you realize that you have missed a deadline, or blow a test because you didn’t have time to study and you might start thinking ‘I’m not good enough’, rather than, ‘I need to develop these muscles and skills’.
Think of it like skiing: if you have never been skiing, at the beginning you fall a lot and you can have sore muscles. But over time, as you learn the skills (both on your own and by finding teachers), and you keep doing it so that the muscles you need for skiing get stronger, you get better and one day you realize that the slope that was scary on Day 1 is actually easy for you now, and you are ready to move up to a more challenging slope.
So, start with just one or two classes the first term, so you can learn the ropes. Be realistic: there will be discouraging days, days when you doubt yourself, days when it seems too much. That is true for every single student I have ever known- me and my friends, the Collegekids and their pals, the college kids that I have taught- everybody. But when it happens to you, you will feel as if you are the only one. So, plan for the hard days. Learn to look for, and ask for, help before things go wrong. And when they do go wrong figure out what your ‘I’ve had a bad day’ treat (one of the Collegekids gets ice cream and watches an old episode of Air Crash Investigations- not sure I want to get into the psychology of that, but it cheers her up!). And then get up, dust yourself off and get back in the game.
This worries me a little: everybody has unforeseen circumstances and everybody has a busy year. It’s not our business, and I am not asking you to share what that was about, but unless you were ‘unable’ to get a job last year b/c you had an unofficial job (such as being the primary caretaker for somebody who required full-time care) and not b/c you couldn’t find one despite looking, think about time management and priorities. A healthy 19 year old who can’t find a job in this labor market rings an alarm bell.