My findings so far in regards to one-shots during Rin-ne's publication

2012
>A Guilty Happening (March 5) = to be dumped on Wednesday

2013
>Inuyasha Epilogue Chapter (February 6) = available
>My Sky (March 5) = *raws on twitter
>I Can't Throw Away Books (November 6) = available
^ this is a short from Rumiko's life
>Revenge Doll (October 10) = Came the Mirror volume

2014
>The Witch and Dinner (March 5) = available
>Someday He'll Get You (July 10) = available
^ another short from her life
>Came the Mirror (July 11) = Came the Mirror volume, naturally

2015
>(Confidentiality) Renaissance (March 5) = *working on it...

2016
>I Hope You Die (March 6) = *found raws
^ the quality of the black and white pages isn't the best (the ink from the other side is visible) but I found them
>She's Coming Tonight (June 6) = available

2017
>A Thousand Years of Innocence (March 22 and 29) = available
>Amorphous Family (April 5) = *found raws

Things aren't as hopeless as you thought OP