Hello Aspirant! No, if you didn't apply for EWS as your category during JEE Mains registration and the result is out as your general result then you are not eligible for the counselling as an EWS candidate. You have to register as a category student before giving the exam failing which can't be helped. You can try another attempt as an EWS candidate in the next year or if your result is good then you can participate in the counselling with that result and get a good college.
Hope this helps.