what happens if I didn't have insurance during some of my military time?
You should have continuous coverage or surrender your plates before being deployed.
what if I couldn't do that?
DMV has a procedure in place to exempt you from administrative actions upon your return. You will have to provide a notarized statement that the vehicle was not used during the time in question, a copy of your military ID, proof of current insurance, and signed and dated copies of deployment and return papers, or DD-214. You can take these documents to any DMV office or mail them.