Iterating through populated rows

For the benefit of anyone searching for similar, see worksheet .UsedRange,
e.g. ? ActiveSheet.UsedRange.Rows.Count
and loops such as
For Each loopRow in Sheets(1).UsedRange.Rows: Print loopRow.Row: Next

It looks like you just hard-coded the row and column; otherwise, a couple of small tweaks, and I think you're there:

Dim sh As Worksheet
Dim rw As Range
Dim RowCount As Integer

RowCount = 0

Set sh = ActiveSheet
For Each rw In sh.Rows

  If sh.Cells(rw.Row, 1).Value = "" Then
    Exit For
  End If

  RowCount = RowCount + 1

Next rw

MsgBox (RowCount)