Has such an occurance happened before ?
"What if" Needs to stop.
"What if" you step outside for a stroll and you're struck with lightning?
There are so many what-ifs but it doesn't work that way.
A poke wouldn't have been a risk. You need to give up on this and move along.
What if I was actually poked with the syringe and not in the bloodstream? Then ?
Somehow your situation seems to be a fabrication of your own mind due to the fear of HIV.
It's very unlikely that a collision against a bag would cause a full injection to your bloodstream. Unless that happens, there would've been no element of a risk.
With almost 36 million people across the globe infected with this virus though unprotected vaginal / anal sex or deliberately sharing needles for drugs abuse with people of questionable serostatus, your exposure would be quite peculiar. The fact of the matter is, it is a story that you are telling your self, shake your self to rationalize before you start believing it and go forward to make it an ordeal for your self.
If you are always fearful of imaginary incidents or some disease or have fear of dying, you should consider seeing a therapist. HIV is not your concern. No testing necessary.