Dinamically calculating based on per week

hi there 

i need a dax formula but in power bi , i have an table , that table has two column , one of the column name is "date" and has some dates , and the other column's name is "quantity" , this quantity named column has some quantities , i want to calculate the total quantity for each week of the current month, where a week starts on Monday and ends on Sunday.

Here is my table : 

i want to calculate the total quantity for each week of the current month, where a week starts on Monday and ends on Sunday , as below table .