19th May is a Sunday, your sample sheet doesn't show Sunday in the required list.
It is included in the total sum of weekly counts.

Do you need it to show as the last entry?

If so change A3 to this, then drag down.
Formula: copy to clipboard 
=IF(COUNTIF($B$2:B2,"")>6,"",IF(A2<=$A$1-7,A2+7,A2+1))

If there is no data for tht date you'll get #/NA in Column D.

The table will not advance until Monday 20 May.