Diaper change arching

I’ve been working towards being able to roll over from my back to my tummy. I still haven’t got the knack for it. Oddly, the closest I get is when I’m getting my diaper change. Recently, I arch my back and twist. It almost looks as if I can turn over, but my head is looking up and back behind me, preventing me from rolling over. I can’t say what I’m trying to achieve by arching or what I’m looking at. It’s just something I do now.