What would be wrong with just saying "meet you saturday 6 pm?" ?

I think you came off a bit too confident and not every woman is into that

You have inspired me to make this meme.

Not everything a woman does or says is a shit test. Quoting my post from a while back, don't be a Red Pill sperg:

not everything a woman does is a shit test! A shit test is when she's attracted to you, but doubts her own attraction due to her innate skepticism bias. Sometimes, a woman is just being shitty. Sometimes, it's just flirty batter (FFS, "why don't you be my photographer?" isn't a goddamn shit test!) and you're already in as long as you don't fuck it up.

In your particular situation, it reads like she's playing around and being flirty. Mess with her a bit; point at her and say "you will do as I say, and you will do it immediately!"

This should be fun. Play with her and make it fun.

She's being a brat. Tell that bitch she's earning some playful spankings.

Give her some handprints on her ass and fuck her face.

She's just being playful bro.

Me: I'll see you Saturday at 6.
Her: "Don't tell me what to do."
Me: I guess I won't then. Walks away

That'll get her hamster spinning: "Is he telling me he won't tell me what to do, or is he telling me I won't see him on Saturday?"

Her: "It's Saturday. I wonder why I haven't seen him?"
Me: Out doing my own thing, fuck that feminist bullshit.

There isn't really enough context here to say whether she is playing with you, whether she actually feels bossed about too much, whether its some feminist nonsense she feels she "ought" to say because you have been very assertive with her in other ways, even if she has liked it.

Until you are sure what it is, I would play it light and take notes. There may be a place for walking away, spanking her or even talking about how she feels but to go down the wrong avenue would be counter productive.

Tell her she needs the guidance since she's being a little baby

Everybody here wants the pussy password.

Be aloof, playful, and assertive only when necessary. This is a generalization, not an exact directive.
Women say all kinds of shit, you should just pay attention to what they do, and otherwise do what you want.

You’re thinking about this too much. You’ve already won.