Ever since I forward faced my son, my carseat doesn't properly fit in my car. I can tighten it as much as I want, add towels and try everything else, but it still slides around and doesn't stay in place. I've looked back to see my son sitting completely sideways in that thing and I'm so worried, because I'm not sure if it's normal that it moves so much. I've had my dad try to tighten it and it still moves. It feels so unsafe to have him in that seat. Is it normal for it to move like it does, or what can I do to make it safer if it's not normal..??