Does anyone know a of a product or method that could help make our queen mattress a little more firm on top? It's not a pillow top mattress, but it's a bit soft on the top and I'm a bit worried about our LO sleeping on it. He's not rolling over yet, but will be soon. I've found extra firm mattress toppers online but they're foam - I haven't tried one, but I suspect they may still be too squishy. Thanks.