I guessed Russian and was wrong.
It is hard to answer such general accent questions and provide useful help in a forum like this. Your English is very good but you can not pass for a native speaker yet. Some of your consonants are wrong, and also your intonation.
If you wish to work independently, my advice is to use voice recorders and news broadcasts. Record what you hear and record your efforts to duplicate it. Then listen hard (AmE) and compare the two.
A quicker but more expensive method is to employ a native speaking coach.
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