What to do from flattened out top half with no underhook

Im a smaller guy and like to smash pass half guard. Sometimes I end up passed the knee shield with a cross face but with no underhook and they keep their elbow tight so I cant get it. I dont like throwing my arm over to try and backstep pass because bigger guys can start squirming and get into octopus guard. Is there anything else I can do from that position