@englishtutor I think I have a similar problem. I have a large vocabulary and can construct useful phrases in certain situations, usually around a transaction of some type, or asking directions or giving simple instructions in a classroom, that type of thing. In other words, phrases built around what I have learned from books, MP3 or app lessons. Memorizing by rote actually. I listen for words I expect to be hearing in response. If I need to buy something from a tool store for example I can teach myself the vocabulary quickly and then do the transaction, but will forget most of the new words later, though retaining the basic phrase parts. I bet you can do this. What you may be saying here is that you cannot carry on spontaneous dialogs or keep conversations going. You may be able, like me, to say phrases that are conversation starters but cannot go no further when the Chinese person begins talking back. Not sure. I am guessing. Chinese people are often the same. They ask you where you are from in English then that is it,they start speaking Chinese.
I think for a lot of people this becomes a place where they get stuck, at a sort of functional survival level, but not at a level that opens doors to social interactions. For me there were several barriers I was never able to overcome. Even though I still self study I doubt I well ever be at a fluent conversational level. I have to accept that now and just improve my survival language skills is all.
For me some issues were: 1) I started learning the language too old. The older the average person gets the harder it becomes to acquire a new language, and Chinese is not an easy language to start off with as your first 2nd language. 2) my listening skills are really poor and this is a common obstacle as well. Chinese people tend to not to like to repeat what they say, speak slowly or use simple words. It is sink or swim in most cases. Add to that the fact the MP3s I listen to ( chinesepod for one) are in Mandarin/Putonghua. And spoken in a slow teacher style. People here in KM speak who knows what, to the point my Chinese wife who speaks Putonghua often does not understand everything she hears so how can I or you. 3) I am too sensitive. This is really important. You have to be tough emotionally to learn Chinese I feel. I hate being laughed at, or over corrected, or told " your Chinese is so bad". I hate people to roll up their eyes or look bewildered when I am speaking some simple phrase like " Qing gei wo cai dan." I keep my cool but often I feel dejected and incompetent or resentful to the listener, and to some degree the listener can be at fault too. But the laughing or harsh criticism is something my type of pesonality will try to avoid, and so I tend to not speak much Chinese though I seem to know more than I think. I taught myself over two hundred characters for example. I can read much of a menu on my own then point rather than try to talk. And lastly 4) and this I think is very important for some people. I am not a super social person. I am not anti-social or a misanthrope but I tend to not be a person dying to talk to people. Add to that I do not know that I would want to talk on an intimate level to all that many Chinese people in a social way. Most of time the questions I am asked in Chinese are like this: where are you from? what is your job in China? How much money do you make? Are you married? Is your wife American or Chinese? Oh, Chinese. Do you have a baby? No baby! Why no baby? Mixed blood is so lovely.
The few near friendships I made with some Chinese guys went south real fast when after one or two meetings they wanted big favors or loans from me and my wife. I almost feel my poor Chinese insulates me from that crap.
Of course I wish I could speak good Chinese. I tried but failed on one level, but on another I taught myself ( I found schools to be rip offs myself, with teachers laughing or rolling up eyes, and doing nothing but tone drills over and over) the Chinese I do know ( believe me, my wife is not my language teacher or translator) and get around ok. I can build on that level, but to get to that high level I hear in other laowai may require of me dedication and effort I simply may not posses.