I suggest you learn English well first for four reasons. First of all, English is the world language. Second, you like it. Third, if you are good at English, you can find a good job before others. Fourth, if you learn Korean before learning English, I can tell you responsibly that your English pronunciation is absolutely inaccurate.

There is nothing wrong with your English listening, speaking, reading and writing, and you still have enough time. It was not too late to learn Korean at that time. Never learn both languages at the same time, so you can't learn both languages well. You can try if you don't believe me.

English training classes, such as New Oriental, Downing Street, Wald, Weber and so on, are many.