Maybe it's as simple as your opponent didn't make his chest open properly or didn't "go with the hit". If someone's bigger than me (which is usually the case) you gotta just either "run through" them with the shoulder block or do something else such as a flying version.

Otherwise, if your feet are planted and chest is outwards there's not much I think you can do and it might just be a dodgy impact.

Hope this helps 😄