Your grammar seems to be 'okay' and it will improve gradually. What I recommend to you is that you extend your reading activity, which means, read as much as you can. Take your start from newspaper because when I started the preparation of CSS exam then I started it from reading newspaper and probably every other aspirant starts from newspaper if they don't have a prior habit of reading. However, in the very beginning, I faced a lot of difficulty comprehending difficult words(which are now easy for me) and understanding grammatical structures of sentences while reading some news article, but I kept this reading activity going on while improving vocabulary and grammar along with it, daily, until I felt that I was ready to start expressing myself through writing. I, then, started making posts about every other petty issue on my FB because I had to improve my writing skill, so I thought FB would be the best place to show off my writing skills to my friends but when I joined this forum later and had conversations with other members then it helped enhance my writing skill a lot more. My suggestion to you is that you involve yourself in real conversations rather writing something on paper and it will hopefully help you. So focus on the following four things which are reading, writing, grammar and vocabulary. As far as the grammar is concerned then there is a popular book named "High School English Grammar" where you can take help from. You just spend at least 20 to 30 minutes daily on grammar and 20 to 30 minutes on learning new words, and if you continue this practice then you will see results within 6 to 7 months.