Save at the first empty row (UserForm- vba)

Hello,
Hope you are doing well
Useing the following code, why the (LastRow) varialbe had the value (270) and start saving from the next row to 270.

Dim LastRow As Integer
With Worksheets("MainDataProject")
LastRow = Sheet1.Cells(Sheet1.Rows.Count, "B").End(xlUp).Row + 1
Cells(LastRow, 2).Value = Me.MainActivitiesPrpjectComboBox.Value
Cells(LastRow, 3).Value = Me.SecodarProActivi1ComboBox.Value
Cells(LastRow, 4).Value = Me.ComboBox13.Value
End With
If LastRow >= 1 Then
Sheet1.Range("A" & LastRow).Value = LastRow + 1
End If
LastRow = WorksheetFunction.CountA(Sheets("MainDataProject").Range("A:D"))

End Sub


HELP PLAESE