You are a human drawn into Equestria by unknown means and meet the cast of My Little Pony.
Also, a lot of mares really want to get into your pants for some reason.

It doesn't matter what you add so long as it's coherent and doesn't include toilet related stuff.
Write at least a paragraph, no one or two sentence chapters, please (unless it's a choice related chapter),
if you add chapters with age regression keep any description of diaper changing light.

...and remember, haaaaave fun with it!