Since my DD-214 was not issued, how can I get it?

First, confirm that one wasn't created for you but never issued (i.e., it's in your records, but a copy wasn't mailed to you).

I'm not familiar with how you can get your records online from the Marines, but any Servicemember can get them through milConnect. Log into milConnect using DS Logon or one of the other authentication methods. Under the "Correspondence/Documentation" window and select "Defense Personnel Records Information (DPRIS)" and then "Request Personnel File". On the next screen, fill out the applicable information and make sure you select your Service (Marine Corps) for the OMPF System. You can specifically look for the DD214, but most just check everything so they get a digital copy of all their records.

If you get a response that your records aren't in the Service digital image OMPF repository database, then submit an online request with the National Archives*.

IF there isn't a DD214 in your records, contact the Military Separations office in the Directorate of Human Resources at Fort Bliss*. Explain your issue and that you have searched your records and a DD214 wasn't in it, explain the background and ask them the next steps.
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* Military Personnel Division, Fort Bliss - https://home.army.mil/bliss/index.php/my-fort/all-services/military-personnel-division
* National Archives online request - https://www.archives.gov/veterans/military-service-records

First, assuming you have access to all the rest of your records from TX ARNG with a DS Logon to here:
https://www.hrcapps.army.mil/portal

and there is no DD-214 there, then start with TX ARNG G1. Your former company, BN or BDE would be unable to help you with a DD-214.
Yes, Ft Bliss demob platform was responsible for this DD-214, and frankly I don't know how you were allowed to leave without going through them, but TX ARNG G1 will have at least one DD-214 operator who can create that 214 for that period of active duty.