Recycling is an excellent way to start thinking about how environmental systems work. What you need to do at this point is just what you're doing: ask lots of questions! Perhaps you could ask to go check out your local recycling center and get a tour. Find out how they separate and sort all the things that people put in their recycling bins, and where they go after that.
To actually practice science and engineering at school, you should ask your guidance counselor what extra technical classes your middle school offers. Many schools will allow you to take a technical drawing class or a computer design class instead of traditional art and drawing class. Also, high schools often have technology classes like robotics, or computer programming but many of students don't really even know about these programs. In these kind of classes, you can learn skills that will be helpful if you want to go to school for engineering or science. And don't be afraid by the number of boys in these kinds of classes! I was usually the only girl in technology classes in high school and it was still really fun for me,
One last thing you can do is to get into any kind of ecology or nature groups in school. Environmental scientists and engineers need to know alot about ecological systems. If your school does not have a club like this, go to the local community center and find out if they do. Even just a gardening club will teach you some useful things about ecology.
Good luck Ta'Lisa!