A young learner like you knows English but has some limits.
At such stage, you need to approach in a scientific way to achieve better performance. You need to start thinking in English. Learn short responses in English. Practice theme-based vocabulary along with Memory Training. You need to hit your weakness from all sides – The Right Way – Within a Reasonable time-frame.
The key to learning a language is to find the Right Balance between Studying & Practicing. Fluency is not all about Grammar; it is about being able to Communicate.
Most Important is: Don’t be afraid to make mistake.