From regular to compostion.. no form available.

I have been in regular scheme upto 28 Sep. Opted for Compositon from 28th Sep. So compostion is effective from 1st Oct. Now I will have to file 3b till Sep and will file gstr4 from Oct. But so far no form option for 3b is showing in return dashbooard for July Aug Sep. Only showing Gst4 for July- Sep which i am not eligible to file as I was in regular for the period. Kindly guide on how to file returns for period from July-Sep.