itch.io

The srd you are linking against is the dnd 3 srd, which you can browse here

https://srd.dndtools.org/

WOTC has at least so far not released a B/X srd, this means the actual numbers your using would not be covered by the srd you are using.

I'm very much not a lawyer, but in general you can't copyright game mechanics. 

This is somewhat a fuzzy line, but I'd feel safe using the generic names and stats you have.

If you wanted to use "Strahd von Zarovich" or other WOTC property thats one thing, but I don't think the names any of the monsters you have are WOTC property. 

Is your notes section on page 23 directly copied? If you wrote it yourself you wouldn't need to worry about that field

If you want to point to something, I'd use either the dnd 5 srd (CC-BY-4.0)
https://www.dndbeyond.com/srd

or something like the basic fantasy rpg srd (CC-BY-4.0)
https://www.basicfantasy.org/srd/

an example monster:
https://www.basicfantasy.org/srd/monstersAll.html#stirge

the bfrg srd is based on b/x and has similar stats as to what your already using

I don't think you strictly need to cite either of these, your page 23 should be fine without copyright assignment, but I'm no lawyer

this is rad! Why is this under both creative commons and the ogl?

To properly license this under the ogl you need to include this license text https://opengamingfoundation.org/ogl.html

You could release this under CC BY-SA 4.0
this would do most of the same things, but make it much easier for other people to use this.
All you'd have to do for that is add "This is released under  CC BY-SA 4.0" or something similar

It also has a bit more health