Yes, I have the same problem ! I can understand people and rarely have any difficulties with reading. But , I cant talk fluently and write as a native can and I always should seek for a proofreading. A friend of mine advised me that I should read lots of english books loudly and in helps me to talk more fluently and also it can make me more familiar with how I can put the words together without reading lots of grammar book and I believe it can work.
Let me know if you receive any better advice.
Student or Learner