Yeah, definitely Saavik's from ST:III
Have you got screenshots? I had a quick flick through the movie and couldn't see it...
Now that I've seen the cast promo shot, I understand why Tom Sutton drew Saavik in that uniform in DC's Star Trek
comic. During the run of issues where Kirk commands the Excelsior
(offically, #17 through #36, though he unofficially commands the Excelsior
midway through the Mirror Universe saga), Sutton drew Saavik with a more casual vest uniform top. For the longest time, I thought that due to Sutton doing his own riff on the uniforms, but now I see that he was following the lead of Star Trek III