Bill missed july17 to july18 not shown in gstr3b and gstr1 invoice given to party they claim itc

Sir

       I am doing retail Sale i have filed GST Every month  till July 2018 both GSTR 1 & GSTR 3B we fail to file the service 9961 GST Details From July 2017 to July 2018 but we gave the bill to party they have claimed the ITC For the bill now only we have found that we have not shown. i am ready to pay the GST amount and Interest ( One of my well wisher said that show all the missed amount in GSTR 3B of August 2018 and pay the interest and show the bill details in GSTR - 1 of August with the bill Date & number  details given to the party ) kindly help me