Hi Dave.
Welcome to the Forum.
It might be your injection technique ? The needle is supposed to be injected into subcutaneous fat, so there is nothing there that should obstruct the needle and cause it to bend.
However, if you hit a muscle or bone when injecting this could be the problem. Do you 'pinch an inch' of flesh when injecting so that you inject solely into a fatty area. If you are slim and not got much fat this could be a problem.
I take it you are not moving the needle when you inject.....they are very fine so that too could bend it.