You can see more movies of foreign.And speaking more with forergner.
morever,you said you do a lot of reading excecises, but do you review it? ask youself why do i make such mistakes?
The most important thing is to communicate, as long as you are able to understand and talk, that'll be all right.
I think you need to use english every day and pratice it more. even you can watch more english porn, that will also helps .