College is an option, but it's not always the answer. Keep your options open. Life is going to bring to you many options, and if you're lucky you will choose a good one, or two. I barely managed high school, and yet I have managed to live a very fulfilled life.
If you think you want to live aboard then get something you can walk around in. Sure a 22ft. boat sounds exciting at first, because it is easier to buy. Try walking around for a week hunched over, or even an hour. With room to walk around you will have room for more than one pair of jeans, and one stinky t-shirt. Even in a fat 30 ftr you will have limited posessions.
There will be time for the opposite sex. I wouldn't worry about moving one aboard. Many men give up their dream, because it doesn't fit the girl friend's dream of a white picket fence, and a knight in shining armor. Your life is meant to be explored, and enjoyed. What will you do with a baby 6 months after the girl moves in, and you have to tell your parents she is pregnant? Think with the big head, and not the little one!
You want to build a boat? Build a rowing dinghy that you can sail. Might cost $500, but it will be there when you get a bigger boat. You will want to get to shore! It is very possible to become rich building boats. Why do you think there are so many manufacturers? Building the dink will give you some experience. You can build one, and sell. Then build a larger one, and sell it. Anything is possible. It was once a dream to put man on the moon too! Maybe at 25 you can build a world cruising cat?
What ever you do be true to yourself, and the right girl will come along in life. Don't throw your dreams , and life away for a little satisfaction that is over in a short time. It took me 50 years to find the right woman for me. In between were a couple of divorces, and way too many girlfriends.
There is no hiway 1 to get through life. Life is a matter of a mountain road full of switch backs, upgrades, and downgrades. Learn to accept that, and push through your problems. Accept the responsibility of your decisions. Don't be a whiner like most of today's kids Alway listen to advice, and then toss most of it out the window. Some of it will be precious, but most is what someone else thinks. Mine included too.
Accomplishments start with a dream, but nothing gets done unless you act on them. The sooner you act the sooner it comes true. If life knocks you down. Pick yourself up, dust yourself off, and push forward with no whining. Hard work with a book, or your hands will see you through life.........i2f