I've been learning german on my own for around five months. In the beginning, I thought the most difficult thing to learn was the verbal conjugations. Okay, I still think it's difficult. But forming a sentence in German when you still lack vocabulary is even worse. What are your strategies for acquiring vocabulary? Books (what kind of books)? Instagram News' profiles in German? Websites? What you think? Eine buch von Goethe?
You should read texts that are interesting to you. That way the motivation stays up high. Especially if translations are unavailable. It gives you a sense of having achieved something.
But it may be a steep climb for a beginner. So, better settle on texts where there are translations readily available. You can find books with German and English aside. You may be specifically interested in the Orange Reihe of the Reclam Verlag, which has a number of books of classic authors in such a two-language style. Also, their books are pretty low-cost. (They also have French, Italian, Russian classics in this series.)
I think this is not a German specific problem. I'm learning Finnish right now and I had the same problem. You are used to how eloquent you are in your mother tounge and naturally want to speak the same way in a foreign language. However, it takes a long time to acquire the vocabulary. Especially in the beginning, the best way in my opinion is to just painfully learn vocabs by hard. Janka has already pointed out a good approach. Learn the vocabulary that you are interested in. I can not recommend Memorion enough as a useful piece of software, especially as app. You can rank yourself in how well you know a word or phrase and it will ask you again in a certain interval. There are prewritten cards for a lot of language pairs but you can also add your own. Because it's an app on my phone, I can literally learn anywhere, anytime. In the bus, waiting in a queue, before I go to sleep and my word pool has increased a lot.