Acl and meniscus problem. Strength back.

Hello doctors, I had torn my acl and meniscus while playing football two years ago, I am a professional football player and I  undergone surgery after six months of injury. It has been 19months since surgery and I still feel instability in my knee.. I couldn't play football on my full potential, it feels like the knee will give up and I will fall down. In less words, my knee is not supporting me completely. I don't have any problem while doing any daily activities i can bend it perfectly but when it comes to doing sudden movements, consider if there is wet somewhere, I have not seen it, and I slips suddenly, the instability occurs. Or zig zag movement in football cause me to fall too. My knee is not completely supporting me and I couldn't play perfectly. Please suggest me some helpful ways with which I can get my strength back.