That looks pretty good. 3 ki is probably a bit much, though, compared with martial adept or metamagic adept, which don’t come with AC bonuses. 2 ki seems better.
Now that I’m thinking of it, that AC bonus makes this feat a no-brainer for the monk. It is definitely better than a Dex ASI for them. I think the feat should probably give 2 ki and trade the AC for a half Dex/Wis ASI. [edit: Actually, even that seems too strong for a short-rest resource. Probably either lose the half ASI, or drop to 1 ki.]
On an unrelated monk note, my brother is far more the student of monk-related practices and philosophies than I. He generally has two big problems with the D&D monk.
One of them (the lack of ability to play them reactively), I addressed with subclass I posted above. The second is broader. He really chafes at the monks’ inability to grapple through precision instead of strength. In his view, the ability to use Dex to grapple should be a part of the monk’s Martial Arts.
I’m inclined to agree, but would also add it to the Grappler feat, which needs help.
Replacing Str (Athletics) with Dex (Athletics) to grapple would be simple enough, but I think it would be better to add Dex to the Str (Athletics). This still makes it useful with barbarian’s advantage to Str checks. Also, I like to provide reasons for Dex-builds not to dump Str and vice versa.