How could i automatically change the col_index_num on a vlookup.

assuming that i got two tab : sheet 1 and sheet 2
sheet 1, is where I am doing the search
sheet 2, is where my data

sheet 2 contain

J 5
F 6
M 7

from the table above, if i do a vlookup("J",sheet1!A:B,2,false) I would get
a result of "5"

let say I need to insert a column in sheet 2, that would look like this

J m 5
F n 6
M o 7

the result on table 1 vlookup("J",sheet1!A:C,2,false) will now be "m"
since I inserted a column, though the table_array automatically adjust, but
the col_index_num remain the same, is there a way to have the col_index_num
to automatically adjust too?

Thanks