1.2k eggs and no shiny, highly doubt shiny charm stacks with MM
I noticed you are using a japanese ditto and an australian froakie. 12k without shiny is weird, same when I was using SPA honedge x ENG honedge. No shiny in 14k eggs.... So I gave up and started using American/Latin pokemon x Japanese pokemon to be absolutely sure that language, region and 3DS/cartridge manufacture differ between them. My friends and I are having the same results that way, getting shinies before 400 hatched eggs. Just a comment, maybe it can help.
I generally keep all the 6 IV offspring (unless I get lots of them) and then only keep the female / low atk offspring to keep stock in my trade thread. I generally send a box into WT for every batch of 100 then release whatever is left over. WT helps take away the monotony of hatching eggs for a while.Just finished another batch of 100 and no luck. Hopefully it's a shiny every other batch, but I'm not going to get my hopes up. Also, is it okay if I swap breeding parents? I might try for a shiny Aron next seeing as how my box is literally filled to the brim with 6IV and 5IV -SpAtk HA Venipedes. How do you guys dispose of your rejects and unwanted babies so quickly? Releasing them seems so wasteful.