ASTB scores are weighed more heavily than GPA, correct? My GPA is over the required 2.5 minimum, but I'm still a little nervous.
This is complete conjecture, but I would assume ASTB is likely weighted most due to the fact that it is the only objective comparison between applicants. You are a little more than 1 SD below the mean GPA of our current (and extremely limited) dataset, which isn't the best place to be, but the fact that it is with a Mech E degree hopefully helps that out some. Given recent board's selection rates and your AQR and PFAR, if I were you I wouldn't be stressing too hard.
Depending on how competitive a school you attended, you may get some help there, as well. I've heard the term "Tier 1" thrown around in my recruiting office regarding school but haven't seen a concrete list of who falls where.