struggling to cope with school

really struggling to manage all my schoolwork. I'm in year 11 and taking English, maths, science, art, drama and history. I'm at a really academic school but the only subjects im doing okay in is drama and art because really im more creative. my mocks are in November and I haven't started revising because I don't understand anything in English or science. literally today my chemistry teacher kept picking on me even though he knew I wouldn't know the answer, It was so humiliating and I don't even want to get extra help in chemistry anymore because he was so horrible. just struggling to even comprehend how im going to start revising for GCSEs. any advice anyone could give me?