I learned Latin in middle school and ancient Greek in high school.
I wanted to learn ancient Greek since I was young, because I loved Greek mythology. But there was no Greek in my school, so I studied Latin instead (Romans almost have the same mythology lol). Latin didn't had success in my school, so we were two different classes with different levels, together, at the same time, with the same teacher. It was terrible, and of course we couldn't keep up with the program with half a teacher.
When I entered high school, I knew I had too much to catch up and I decided to give up Latin, and I studied Greek only, and it was awesome <3
But like everything at school, if you don't keep using what you study, you forget everything.
Have you ever tried Duolingo to learn a language?