I think the first step since you already have been a passenger on the ocean. Would be to take those lessons of sailing, and living on the boat. Hopefully somewhere warm.
If that goes well then it's time to look for a boat. In the mean time READ, READ, READ, and ask questions. No one can tell you what boat to buy, so you will need to do research, research, research.
Let's assume the lesson went well, and you are still motivated to live aboard. Upon returning I would take more lessons, or rent small daysailors to practice your new knowledge, because I know you have been reading this whole time with no rest from gathering knowledge. Now that you have been stuffing those empty pidgeon holes in your brain that young people seem to posess. You can start throwing some of that new knowledge in the trash, and retain some of it.
All this time you have been walking docks, yards, and looking through boats for sale where ever you can. All so you can find what is pleasing to your eye, and within your budget. You may find that you have enough cash, or close to enough to barter a outright purchase of a boat. Having a title means a lot. It means you can start saving for your next boat, because if living aboard is for you. You will eventually want more boat, and owning the first one will allow you to save money for it.
After a couple of years of living on the boat. Making new friends who sail, and have boats. Honing your skills on your very own boat, and possibly others. Still reading, and gathering knowledge. Still keeping your eyes open for that look that really turns your head. Understanding what sails well for the purpose of what you want in a boat.
Do you want to cruise oceans, and explore other peoples? Do you want to race her on Friday night around the cans? Do want a wee bit of both? This knowledge does not come over night, and no one can stuff it in your brain overnight. You can listen to advice, and dismiss what you want to. If you are lucky you will find a mentor. Someone who has been there, and done that. Someone who is willing to share the knowledge that took them decades to learn. A mentor is a great shortcut to seek out what you wish to learn.
Stay away from the slick magazines with the pretty pictures. Go to second hand bookstores where the books are worn, and well read. Gather knowledge from those who aren't out to sell you something, but are sharing their experiences. Read the forums, and soak it up.
You can have a catamaran if you want. Most likely you just can't have it right now. Sailing is like anything else in life. You have to crawl before you can walk, and then you can learn to run. If you really want something then you have to stay focused. BEST WISHES in it working out for you. It's not hard it's just a step at a time.