I have solved around (45) 1400 rating questions and (35) 1500 rating questions and in total around 540 questions and I'm still not able to improve my rating , how can I improve my rating and speed , what am I lacking (I don't know DP)

I have been solving questions continuously for the past 60+ days and I feel that there is no big improvement , I accept the fact that it will take some time to improve , but at this stage what all should I learn (any new algorithms -like binary search bitmasks ) and which set of problems should start solving (as of now I'm trying from C2- ladders (1000-1200) level .