Finding sgi files to upload sims

Hi there!

I'm trying to upload a sim I've made outside the Gallery. I know I need to find 5 files (1 householdinary file, 1 trayitem file, 1sgi file and 2 hhi files) in the Tray folder within the Sims 4 folder. I can find all but the sgi file. I've gone back into create-a-sim and re-saved the sim, then sorted all files in the Tray by date. Still no sign of the sgi file. Can anyone shed any light on this? I've spent ages on this sim and would love to be able to upload it on my Tumblr. 

Any help would be much appreciated!