It's true that young children can pick up accents better than adults. Not many people who start learning a language when they are adults get to the stage where they can pass as native speakers, but it is very unlikely that you have reached a ceiling after a year beyond which you cannot go. In the early stages of learning, it is quite easy to measure your progress, but this becomes more difficult at advanced level and this can lead to some frustration, especially if you're comparing yourself with native speakers. You say that people don't understand sometimes; I'd start by trying to analyse these situations in some detail and trying to get to the causes and look for strategies to improve things. The short conversations and transactions we have, for instance, often don't give the listener much time to focus on an unfamiliar pronunciation, so if all the keywords are right at the beginning, they may not be understood.
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