So, answering the question fully - here's the story.
I went to an art school when I was a kid. For I don't actually remember how long. I had to quit because... well, I had too much going on - school, piano classes, English tutor, math tutor, dance classes, choir... oh my.
Russian kids do grow up being forced a lot to play Chaikowsky on various instruments:) I sort of wanted to do something else apart from all the "obligatory" music program. I still remember a lot of theory from my art school, and I'm very grateful for having this experience. Unfortunately I dropped out to continue with the piano (which, obviously, I don't play any more).
Since I started experimenting with painting, I've gone through maaaany online classes and workshops. I've also completed a full online course on oil painting. I took every opportunity to learn online, because where I live there's almost no options to educate yourself otherwise, it's a countryside and we don't have art schools or courses for adults. I attended a few classes in the nearby city though, and that's where I learned about an American artist Carol Marine. Her concept of "daily painting" set me free! The idea of daily painting is that you paint small size and as often as you can. Anything you want. This way you learn faster, you don't kill yourself trying to complete a big canvas with too many details, you focus on what you like and in the end if the painting didn't work out, you just get rid of it with no hard feelings. And start over. Key to success - start over, try again, try again and so on. Loved it :)
I've also taken a lot from books, and I keep learning every day. Besides "Daily painting", I've read a number of instructional books on oil painting, and the one I loved the most is "Landscape painting essentials" by Johannes Vloothius. His technique is applicable to all the other genres as well, so I refer to his instructions pretty often.
Of course there's no limit to what you can learn. In fact, being an artist you never stop learning. It's important to be able to see the imperfections and mistakes in your work, so you could move on from those. But it should never stop you from trying again, because you can't get worse at it, only better. And not having a degree has never stopped a person passionate enough to pursue their path!