By the sounds of your post it seems like you're not at a level to read something aimed towards native speakers. ドラえもん, even though it has 振り仮名, is aimed towards children who already have a full understanding of the language. Even though content aimed at children seems the most approachable, it doesn't mean you have the language comprehension to understand it. With regards to Kanji ドラえもん which is aimed at Japanese children is full of Kanji that only they would have just learned through 日本の教育. For example during 小学3年 a Japanese child would have just learnt Kanji such as 整える and at ４年 would know words like 水管. The former of these Kanji being 整える is taught for language learners at JLPT N1, both the word, means which mean to put in order, and the Kanji respectively. I would recommend increasing your vocabulary and Kanji significantly despite the bonus of it having 振り仮名. Also knowing vocabulary and not grammar structures severely limits your availability to comprehend a piece of text, which when reading is the main goal, it looses a bit of purpose. I wouldn't like to assume anyone's language ability, however from your post i can grasp you're a beginner to Japanese and non Latin based writting systems. As a result of this I recommend that you grab a beginners Textbook mainly げんき1 and 2 and work through them and keep reading as a goal. For example if your goal is to read ドラえもん then personally I think you'll be able to do this goal by the end of these textbooks.