TOTALYTD using variable year end date

Hi

I am using this formula for running total:

No issues with this but I am also using a parameter based on month int:

I need the year end date to change in the formula.

I have tried to use the power query editor to create a concatenated value:

[Query="
declare @StartMonthInt int; set @StartMonthInt = '"&Start_Month_Int&"'

declare @CurrentFY int; set @CurrentFY =
(
select
case when [MonthNum] < @StartMonthInt then datepart(yy,dateadd(year, -1, [DateFull]))

else year([DateFull]) end

from [CommRS_Core_Live].[dbo].[RS_Dates]

where
[DateFull] = cast(getdate() as date)
)

declare @FYStartDate date; set @FYStartDate =
(
select
min([DateFull])

from [CommRS_Core_Live].[dbo].[RS_Dates]

where
datepart(yy,[DateFull]) = @CurrentFY

and datepart(mm,[DateFull]) = @StartMonthInt
)

declare @FYEndDate date; set @FYEndDate = (select dateadd(dd, -1, dateadd(year, 1, @FYStartDate)))

--select '" & "' + cast(datepart(dd,@FYEndDate) as varchar(2)) + '/' + cast(datepart(mm,@FYEndDate) as varchar(2)) + '" & """' [FY end dd/mm]

select @FYEndDate [FY end]
"]),
#"Duplicated Column" = Table.DuplicateColumn(Source, "FY end", "FY end - Copy"),
#"Extracted Day" = Table.TransformColumns(#"Duplicated Column",{{"FY end - Copy", Date.Day, Int64.Type}}),
#"Changed Type" = Table.TransformColumnTypes(#"Extracted Day",{{"FY end - Copy", type text}}),
#"Renamed Columns" = Table.RenameColumns(#"Changed Type",{{"FY end - Copy", "FY end - Day"}}),
#"Duplicated Column1" = Table.DuplicateColumn(#"Renamed Columns", "FY end", "FY end - Copy"),
#"Extracted Month" = Table.TransformColumns(#"Duplicated Column1",{{"FY end - Copy", Date.Month, Int64.Type}}),
#"Changed Type1" = Table.TransformColumnTypes(#"Extracted Month",{{"FY end - Copy", type text}}),
#"Renamed Columns1" = Table.RenameColumns(#"Changed Type1",{{"FY end - Copy", "FY end - Month"}}),
#"Added Custom" = Table.AddColumn(#"Renamed Columns1", "Custom", each Text.Combine({[#"FY end - Day"],[#"FY end - Month"]},"/")),
#"Renamed Columns2" = Table.RenameColumns(#"Added Custom",{{"Custom", "FY end dd/mm"}})
in
#"Renamed Columns2"

I then passed this through to the formula like so:

However it looks as though the formula is defaulting to 31/1 rather than 31/3 (in this instance where parameter value is 4, ie April):

Do you have any idea how I can "trick" the TOTALYTD formula into accepting the concatenated value as a date value, or is there an alternative?

Cheers