Transposing an Array and Autofilling - arrays

Question

I'm looking for a more efficient, less hard-coded way of transposing an array and then autofilling formulas in adjacent columns. Here is my current code for transposing my array in a specific spot on the sheet and autofilling the columns:
If Len(Join(myArray)) > 0 Then
ActiveWorkbook.Sheets("Delta Summary").Range("A3:A" & UBound(myArray) + 2) = WorksheetFunction.Transpose(myArray)
ActiveWorkbook.Sheets("Delta Summary").Range("B3").Select
Range(Selection, Selection.End(xlToRight)).Select
Selection.AutoFill Destination:=Range("B3:K17"), Type:=xlFillDefault
Else: End If
The goal is to transpose the array starting in cell A3 on sheet "Delta Summary". My code accomplishes this, but I'm wondering if there's a better way to do it. For reference, I loop through this array and transpose it several times based on different criteria. I transpose the array beginning at cells A3, A20, A37,..., and A224. Each section has 15 cells allocated for data.
As for the auto-fill, I'd like to auto-fill the formulas in columns B:K down to the last populated cell in column A for that pre-defined range (ex. A3:A17, A20:34, etc.). I don't know how to find the last populated cell for a pre-defined range, so I have this hardcoded.
I'm still learning, so any insight would be greatly appreciated!
Edit: Here is one example of the looping criteria I use to populate my array:
ReDim myArray(0)
For i = 1 To LastCurrID
If ActiveWorkbook.Sheets("Weekly Comparison").Range("N" & i) = "N" And ActiveWorkbook.Sheets("Weekly Comparison").Range("J" & i) = "Billing" Then
myArray(UBound(myArray)) = ActiveWorkbook.Sheets("Weekly Comparison").Range("A" & i)
ReDim Preserve myArray(UBound(myArray) + 1)
End If
Next i
Edit #2: For those who are curious, here's the completed code. I only slightly changed what was commented below.
ReDim myArray(0)
For i = 1 To LastCurrID
If wkb.Sheets("Weekly Comparison").Range("N" & i) = "N" And wkb.Sheets("Weekly Comparison").Range("J" & i) = "Billing" Then
myArray(UBound(myArray)) = wkb.Sheets("Weekly Comparison").Range("A" & i)
ReDim Preserve myArray(UBound(myArray) + 1)
End If
Next i
For y = LBound(myArray) To UBound(myArray)
If Len(Join(myArray)) > 0 Then
With wks
.Range("A" & x & ":A" & UBound(myArray) + x - 1) = WorksheetFunction.Transpose(myArray)
Dim lRow As Long
lRow = .Range("A" & x).End(xlDown).Row - x + 1
.Range("B" & x).Resize(1, 10).AutoFill _
Destination:=.Range("B" & x).Resize(lRow, 10), Type:=xlFillDefault
End With
End If
Next
x = x + 17

Answer 1

EDIT (Based on OP Update Question with Looping)
From the way you build your array, it seems like the array is loading with the last row of the data range to be copied (within the 15 row limit) for each range.
The below will loop through the array again, and will set a factor of 17 to x for each loop (starting at 3) and will find the last row within the specified range starting at 'Bx' and uses the .Resize method to do the AutoFill:
'always best to qualify the workbook, worksheet objects with a variable
Dim wkb As Workbook, wks As Worksheet
Set wkb = Workbooks("myWKb")
Set wks = wkb.Sheets("Delta Summary")
Dim x As Long, y As Long
x = 3
For y = LBound(myArray) To UBound(myArray)
If Len(Join(myArray)) > 0 Then
With wks
.Range("A" & x & ":A" & UBound(myArray) + 2) = WorksheetFunction.Transpose(myArray)
Dim lRow As Long
lRow = .Range("A" & x).End(xlDown).Row
.Range("B" & x).Resize(1, 10).AutoFill _
Destination:=.Range("B" & x).Resize(lRow, 10), Type:=xlFillDefault
End With
End If
x = x + 17
Next