...before I had experience with actually riding, i already knew how. Then i started riding and I was really good at it.. and then i stopped...I'm just at the point where i don't need someone to instruct me how to do these things and even when I was taking lessons, i was getting there and feeling awkward when I'd be told what to do and I knew i could do it myself. Riding was really calming/enjoyable for me and if I could spend time with a horse without another person watching me/telling me what to do, would be extremely nice. I won't ever be able to afford a horse or to lease and I don't know how everything works, especially the etiquette.
If you truly "won't ever" be able to own or lease a horse, then you will always have to be open to having whoever owns the horse tell you what they want to do and how they want you to ride. I'd say no matter what your age, it's a good goal to work toward being able to afford a horse if you would like to own one. That might mean taking a couple years off riding and going to college, etc.
I'm not sure what you're saying exactly when you say you "already knew how" to ride. It could be you mean you read lots of books and watched videos and learned many theories about riding. That's great. But if you're trying to say you had some sort of "natural" ability, that's not going to take you very far. Even if you are athletic and balanced you need to understand many other principles and practice many things before you can be a good rider.
I'd say you're a good rider if several professionals and other very good riders tell you that you are. Those who base their assessment of their own riding ability on how they feel they are doing will soon be humbled by a horse that is difficult to handle. It was difficult for me to say I was a good rider until I was trying to assess myself for riding at stables overseas. They had criteria to help them decide if you were a good rider. One was based on how many rides you had on a horse, i.e. under a hundred rides meant you were a rank beginner. Another criteria was that you were an experienced rider if you could get on a strange horse and gallop him over open country you hadn't ridden on before. When I could honestly say I could do that without putting myself or the horse in danger (not talking about a totally inexperienced horse), then I was willing to say I was a "good" rider.
If I were you, I'd try to meet someone who has an extra horse you can ride. But I'd expect them to assess your riding skills for a few rides and perhaps ride out with you on another horse for a few rides before they let you go out on their own. They won't want you to hurt their horse, but they also won't want you to get hurt. I've had two people tell me they were "great" riders but both of them fell off on the first ride so now I spend some time assessing people who want to ride my horses and give them some lessons myself if necessary.
Also, "knowing how to ride" may only apply to one type of horse or one discipline. I don't know how to ride every discipline, and whenever I ride someone else's horse I have them instruct me on how the horse has been trained. Does the horse neck rein or direct rein? What kind of seat do they prefer? Do they move off your legs or do they not understand leg contact? How you ride also depends on what type of bit/headgear the horse is wearing. There are many, many different forms of riding. No one can know how to do them all with excellence.