Maybe, I'm missing something: On your (btw. really great) site I read:
"It will only send it as a private message if you use “dm” in small letters. The phrase “DM” in capital letters will be ignored and the reminder will be public."
... but, according to the Dev:
"... both "dm" and "DM" will result in the bot replying in a direct message (instead of publicly)"
BTW, will this message be visible to you only - because of the mention at the very beginning of the post?