Slicer with weekly date range

I have a data source which has a range of weekly metrics. I want to filter all the page by weekly dates. 

For example, I can filter from the 1st Dec to 1st Jan or 17th Dec to 9th Jan. I want to be able to filter by any start or end dates and it would sum up the sessions or visitors etc for those dates I chose. 

Currently when I click on 1st Dec it only allows my end date to be 8th Dec. Please help