I'm a bit concerned at this point because I e-filed on the 16th and still have not seen any changes to status. Site would also not allow my to file an extension.

As long as you haven't received any message by this time that your tax return was "rejected," then the odds are very good that it will be e-file "accepted" by the government.

In the unlikely event that it is not, and your tax return is ultimately sent back to you as "rejected," then you generally have a 5-day grace period in which to correct whatever the problem may be, and then to e-file the tax return again -- or to print and mail the tax return instead.  (Either way will prevent you from being considered "late," and thus an extension is not necessary.)

When and if doing the latter (paper-filing after an e-file rejection), you can help your case that you tried to (e-file) in a timely manner by printing your rejection sheet, and including that along with your paper-filed state tax return as an attachment.

However, none of that will be necessary if your tax return is eventually e-file "accepted."  Simply as an observation, sometimes it takes a few days for the e-file process to clear the system, and notification confirmation to filter back to the taxpayer.  This is especially true during a busy time of year (mid-April) for filing tax returns.  Thus, seeing a status of "pending," or otherwise, for a few days is not unusual.

Thank you for asking this important question.