For a B1-B2 learner, the best next step is to pick content you already know and love in English but in a simpler format, like translated middle-grade fiction or popular comics. This reduces cognitive load so you can focus on language patterns rather than plot. Your list of The Little Prince and Harry Potter is excellent, but if those feel too hard, try shorter, dialogue-heavy comics or news summaries first.
At B1-B2, the main barriers are unknown vocabulary, speed of native speech, and colloquial expressions. To overcome these, choose materials with high frequency words and clear context. For reading, consider translated versions of books you know well, like the first Harry Potter or a Star Wars novelization for younger readers. Comics like "Asterix" or "Tintin" have visual cues that aid comprehension. For listening, start with podcasts designed for learners, then move to slower, clear-speaking native podcasts about topics you enjoy, like history or science. News sites often have a "simple language" section (like NOS Jeugdjournaal in Dutch) that uses controlled vocabulary.
A practical approach is to use a combination of extensive and intensive reading. For extensive reading, pick something where you understand 90-95% of words without a dictionary; read for pleasure, guessing unknown words from context. For intensive reading, take a short passage (a paragraph or page) and look up every unknown word, then reread it aloud. This builds both fluency and precision.
Honest tradeoffs: Graded readers are boring but efficient. Native content is engaging but slow going. You'll need patience. Start with 10-15 minutes daily, not hours. Use a tool like a pop-up dictionary or a reading app that lets you save words. For listening, turn on subtitles in Dutch first, then remove them as you improve.
Concrete next steps: This week, find one Dutch comic or a short news article on a topic you love. Read it without a dictionary first to see how much you grasp. Then reread with help. Next, find a 5-minute podcast episode on a familiar subject and listen twice: once with a transcript, once without. Track your unknown words and review them with spaced repetition. In a month, you'll notice your comfort zone expand.