My response rate doesnt go up after answering messages

If you're really sure that you don't have more unanswered conversations, then i suggest to contact the support - this metric is known to be buggy sometimes.

P.S. be aware that numerous spam messages that you may receive on this site, also counts to response rate and time. I always write short response to spam messages (usualy it's FU) and then press report button. That way i keep my records at good shape.