If I have 6 or 7 months remaining on my GI Bill, can I get an extension to finish out the year and a half left that I have until graduating?

I was able to extend my benefits by switching from Post 9/11 GI Bill to Voc Rehab when I exhausted the former.

You MAY be able to use education benefits under VR&E if you meet eligibility requirements for the VR&E program. IF by chance you are using benefits under MGIB-AD and if you have multiple periods of service and you use all months under MGIB-AD you can request an additional 12 months under Post 9-11, but that is the only way you can get the additional 12 months.

Apart from that VR&E education benefits can be extended out to 48 months as well, mentioned below. But the key is that you must be eligible; for example, you must have at least a 10 percent VA service-connected disability rating that limits your ability to work certain jobs.

In this case, you should talk with your nearest VA VetSuccess counselor about extending it (if it's STEM-related) or VocRehab Chap.33 if not STEM.
https://www.benefits.va.gov/vocrehab/vsoc.asp