Using VBA to vlookup date in range, and return cell value based upon variable critera

I’m a relative novice on VBA, but feel like this should be quite simple. I just can’t seem to get anything to work.

I have a ‘master’ tab called “Total outcome” in which I have a range of dates in column B (from TODAY() to 2 years forward) and a number of columns (C to G in this example) with subtitles corresponding to the other tab names.

I’m looking for a method of looking up the date in the “Total outcome” tab in each tab and returning a +ive number if the cell title reads “…Purchases” and returning a -ive number if the column subtitle reads “…Sales” in the corresponding column. In each case the title will be “My Purchases” or “My Sales” in each tab.

I’d appreciate any help you could provide! Thank you so much