AutoFill Macro when blank cell in different column

Hi There,

I could really use some help with writing a macro to help me autofill a formula when a blank cell comes up in a different cell. I've looked at some others and tried to modify them but keep messing up.

In the attached image you'll see I am trying to build an address by inputting the code =CONCATENATE(B3," ",$A$2) which would produce 1012 A ST in cell C3. I would like it to autofill the formula down until it hits the next street which in the example is A12 which is B ST . I wanted the macro to autofill until there was a blank cell in the B column. I found this to be the best method.

The only other thing is I need 2 macro's because my field names change when there is a predirection such as 1012 S. 12th St. So I use the formula =CONCATENATE(B3," ",D3, " ", $A$2). I'm assuming I could just substitute the formula out in the macro code.

If anyone could help me I would appreciate it. I am going to post two other parts of code that I was working with for reference, although they are doing different things.

Thanks,
Brett

Sub filldata()
Range(Range("B2"), Cells(Rows.Count, 3).End(xlUp).Offset(, -1)). _
SpecialCells(xlCellTypeBlanks).FormulaR1C1 = "=R[-1]C"
With Columns("B")
.Value = .Value
End With
End Sub