Best place to put a car seat?

I stress out way too much over this because it honestly just scares me. I usually have my sons car seat in the middle seat, I was told that was the safest place, and it makes since. But I recently got a new car and the middle seat has like a hump on it and my sons car seat doesn’t fit right and the seat belt won’t get tight enough on the car seat and it wobbles unless I tighten it every time I get him out and put him in. The manual doesn’t say anything about it. Is it any less safer to put him on either side? Or should I just keep him in the middle?