See it would be cheaper if mom was the primary but the way NJM works is that since there are two drivers on the policy and two cars, there has to be a primary for each so she can't be the primary for both and have me drive as a secondary or else it would be cheaper.
It works for me though I'm graduating in May and assuming I find a job ~200 a month isn't all that bad for insurance. It'll eventually drop over time.
In the meantime I plan to look around to see if there are any better rates but i highly doubt anything is better than NJM. They're almost impossible to join in the first place.