Your best bet would be to look at each files history, which is usually displayed similar to this:
MapName.fhm -- 01/06/2014--FHM FILE -- SizeOfFileGoesHere
MapFromTwoYearsAgo.fhm-- 23/10/212 -- FHM FILE -- SizeOfFileGoesHere
If you still have trouble, wait a day or two and re export the map you want to compress and look for the most recently modified map files in exports like shown above. If it doesn't say the last time the files were modified on your PC, right click the file you want to examine and go to properties. It might be listed there.
I'm not sure there's another way to get the right files if you were messing around with most of the files that sane day, but if there is, please someone say. c: