I think pullet. I’m no expert but I’ve had a little experience that makes me willing to make a guess.
We started with three speckled Sussex chicks in our little flock, purchased as females but two turned out to be Roos. Within a few weeks there were differences obvious even to me, a complete novice. Long story short (which is hard for me when it comes to chickens) the one pullet, Miss Sparky, looked at that age significantly like yours, posture and all. And she does move a little differently, with more of a rolling gate than the pterodactyl stride you see in a lot of breeds.
I will add, she‘s turned out to be the friendliest and most personable bird in the flock; well, maybe behind the Creves.