Gstr 3b reg

Sir,

April 2019 Sales 5 lacks. but May Sales 35,000 and goods returned 2.15 lacks. we are filed April 2019 3B and GSTR1 but we cannot file 3B for the month of May 2019 because of goods returned (215000-35000) 180000. How to file 3B return. i have also entered in GSTR 1 for the month of May 2019 for goods returned 2.15 lacks issuing of credit notes and not file in GSTR 1. How to match 3 B and GSTR 1. Pl clarify the above.