Surely you speak and write pretty much fluent English to get offered a place?
Your OP is perfectly understandable for instance, it's not structured exactly how an English person would, but it's as you would expect from someone who learnt English as a second language and is pretty much fluent.
I bet the biggest challenge is your accent, a guy I work with had this problem. He just told us to tell him when he was difficult to understand so he knows where he needs to improve, maybe try this with people you become friends with to improve your speaking.