need help with sql query

HI ALL

I want to find out number of game wins and cumulative game wins from their live date. I have the sql query ready but the weekno in my query is somewhat incorrect. Their is a difference of +1week/-1 week on spot checking the actual data.

The weekno i have to calculate is based on golivedate which falls sometime on weekday or on weekend.A weekno is defined as a week between 1 sunday to another sunday of any date. 

I have another table which is the date table and the relevant column is week_ending for that. I have tried to change my query and take week_Ending date but it doesnt match up.

For example on spot check .their are few more also 

select DATEDIFF(week,'2018-11-22','2020-03-22') ----->70 but i am getting 69

here ''2018-11-22' is golive date and i can find the right weekending date when joined with date table

Scrrenshot:-

My original query which is correct apart from weeknumber

;with cte as 
(
select game,sum(real_gw)as Costs,cast(LAST_DAY_OF_WEEK as date) as [date]
from [one_data]
group by game,cast(LAST_DAY_OF_WEEK as date)
)
select * from
(
SELECT game, Costs,[Date],
       datediff(week, first_value([Date]) OVER(PARTITION BY game ORDER BY [date]), [Date]) AS weeknumber,
       SUM(Costs) OVER(PARTITION BY game
                      ORDER BY [date]
                      ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS total
FROM  cte
)a
where weeknumber>53
ORDER  BY GAME asc,date asc

Query which i tried to modify but it didnt help to get the right weekno and that is

;with cte as 
(
select game,sum(real_gw)as Costs,cast(LAST_DAY_OF_WEEK as date) as [date],[Week Ending]
from [onetruth_data] a
inner join 
Md_Date_Table b
on a.GoLive_Date = b.Date
group by game,cast(LAST_DAY_OF_WEEK as date),[Week Ending]
)
select * from
(
SELECT game, Costs,[Date],
       datediff(week, first_value([Week Ending]) OVER(PARTITION BY game ORDER BY [week ending]), date) AS weeknumber,
       SUM(Costs) OVER(PARTITION BY game
                      ORDER BY [date]
                      ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS total
FROM  cte
)a
where weeknumber>53
ORDER  BY GAME asc,date asc

Result is the same on both query as you see in screenshot

Any help can be appreciated

Regards

Farhan Jamil