After six months under review and after an e-mail to the editor
For what it's worth, May 5 was likely in the middle of the end-of-semester rush of projects, make-up student work, writing and giving and grading final exams, meeting with students who need at least Grade X to graduate, etc. In addition to this, your email could have gotten lost in the avalanche of student and administrative emails during this time. On the other hand, presumably an editor would have weathered this many times before . . .

I suggest looking at the calendar for the college/university the editor is affiliated with, and after the spring semester has been officially over about a week, I think it would be reasonable to send another (polite) email.