Hi I am trying to make a homebrew subclass for a monk that uses spell slots.

I have followed every step to make it.

I have set WIS for spellcasting ability, yes on "can cast spells", added wizard and druid spell list and left both "spell prepare type" and "know all spells" blank while adding Spellcasting (wrote correctly) as a 3rd level feature and granted. 

I had to fill the description with something? Because I can't leave it empty. 

What am I doing wrong? Because spell slots don't appear in the sheet.

Please see the General FAQ #s 6 through 6-B: (https://www.dndbeyond.com/forums/dungeons-dragons-discussion/homebrew-house-rules/131411-a-homebrewers-how-to-faq).

I have done what was listed, nothing has changed 

You re-saved the whole subclass, waited 20 minutes, and then made sure to “wake up” your character sheet and refresh it? Try waking it up and refreshing it again. Sometimes it can take a while. If that doesn’t fix it then triple check you set up the subclass correctly.

Did you get it sorted out?

Somewhat, apparently I had to add the amount of spell know for the subclass ... I think 

Shouldn’t have had to, you can’t change that from the standard number even if you try.  It was probably the re-save and the extra time. But it’s working now which is what matters.