Looks like this one to me: Valentinian II AE3. 378-383 AD. DN VALENTIANVS IVN PF AVG, pearl-diademed, draped and cuirassed bust right / VRBS ROMA, Roma seated on cuirass, holding spear and Victory on globe. Star in right field. Mintmark ANTB.
You most assuredly did. It's an VRBS ROMA type of Valentinian II (IVN after the name differentiates Valentinian I from Valentinian II). It's also a nice example of this Emperor.
Yes, you are correct in attributing it to Valentinian II. However, I think it's RIC 34 from Nicomedia, not RIC 51 from Antioch - the mintmark seems to be SMNB, not ANTB. Here's an example with the same mintmark: http://www.forumancientcoins.com/gallery/displayimage.php?pos=-133445