My US residency is a mess.

I was in state A for a long time, where I voted last time. I had to renew my drivers license from state B, because I was temporarily there for a contract before going back to school when my license expired. So I have a license from state A with an address at state B. I intended to return to state A after grad school but life changes and that’s no longer the plan.

I’ve been a student in Canada for years now with no ties to my original address or even the state B address from my license. My parents live in state C, but I don’t have anything current tying me there, either. I haven’t had a state C license or address since high school.

Where/how can I register to vote with everything currently tied to my canadian address?

Thanks for any advice… This has been bothering me and my last midterm ballot for state A was rejected because I think I was purged.