Using INDEX/MATCH with variable column names

I have a spreadsheet that I use to track our monthly incoming and outgoing products. Right now, I'm using an INDEX/MATCH formula to pull data from other worksheets, which works fairly well. The only problem is that each month, as I rotate months on my report, I have to go through and update my formulas to pull from the appropriate columns which can be a bit time consuming.

Here's the current formula that I'm using:
=INDEX('Incoming orders'!R:R,MATCH(C4,'Incoming orders'!A:A,0))

In this formula, the 'Incoming orders'!R:R refers to the column labeled "MAY" on the 'Incoming orders' worksheet. But next month, I will be shifting all of the months again, so then that first column will be for JUNE instead of MAY.

Is there any way I can use the INDEX/MATCH function to pull from the column that corresponds to the value at L2 (the 1st month)?

EDIT: Attached is a sample worksheet for reference.

The INDEX() function can take up to three arguments (yours only has two). The first argument is the range to extract from, the second argument is the desired row # from that range, and the third argument is the desired column #. When I want to do something like what you are describing, I use a 2D range reference for the first argument, and specify (by whatever algorithm makes sense to the given problem) both the row number and column number. In your case, it might make sense to use two MATCH() functions, one for the row # and one for the column #. Maybe something like: =INDEX('Incoming orders'!$E$1:$AE$44,MATCH(C4,'Incoming orders'!A:A,0),match(J$2,'Incoming orders'!$E$1:$AE$1,0)) or whatever algorithm works for specifying that you want to pull from row # and col # of the incoming orders spreadsheet.