userform feeding into worksheets

Take a look at the database form example

Private Sub cmd_Save_Click()

  Dim NextRw As Long
    
  With Sheets("Requests Fullfilled")
  NextRw = .Cells(.Rows.Count, 1).End(xlUp).Row = 1
  'not sure why, your code overwrites
  ' .Cells(NextRw, 1).Value = cmb_Item.Value
   .Cells(NextRw, 1).Value = txt_Date.Value
   .Cells(NextRw, 2).Value = txt_CostCentre.Value