Don't worry - you are not alone! I'm not a language learning professional, but I personally feel that reading/writing and speaking/listening comprehension are two completely different skill sets. I've attended plenty of foreign language classes where students were amazing with reading and writing but literally could not speak a complete sentence, even at a B2 level. I had a conversation partner once who insisted on typing everything into her smartphone translator and letting it speak for her!
While more reading and writing (online forums as others have suggested) is always helpful, I think the only REAL solution is just to get out there and talk with humans using your own voice. Yes, it is frustrating. No, you can't say exactly what you want. Yes, sometimes the people who you are talking to will treat you like a child because of your level of language (I can't tell you how frustrated I get with that aspect on a daily basis here in Germany). No, you will not make overnight miraculous progress and one day just wake up and be fluent. But YES, it will be baby steps until you DO feel like you can say what you want. :-)