Melody-sings,

Yes, you could have suffered a whiplash injury but I doubt it could be more than a minor whiplash event. Your back was not against or impacted by a seat back so your whole spine was able to absorb the whiplash force so less effected your neck and head. This could not be as severe as a car rear-ender collision because your entire body was able to absorb the forces, including moving on your seat.

Yes, it can be startling and that can make even minor sensations appear to be much more severe.

It sounds like you did not manifest any noticeable symptoms. There is no reason to look for an injury. Human nature is such that when one looks for an injury, symptoms will manifest that were not evident before "looking" for the injury.

Don't go looking for Dr Cameron at Complete Concussion Management to tell you that you have whiplash. He tends to exaggerate.