If you didn't receive a confirmation email and you met the deadline, I would recommend that you check your spam folder. If you don't find a confirmation email there, then I would recommend that you find your original submission email in your sent folder (complete with date sent) and forward it to
submissions@topcow.com with a note explaining that you never received confirmation and are concerned about it. The Top Cow crew have been cool about technical difficulties and things of that nature in the past.
Good luck!