BBM
The fact that OP had his arm on the wall for balance and leaned back against the wall makes perfect sense, whatever speed OP's traveling at.
Below the knee amputation often necessitates the need to hold or lean against something stable, especially once you stop moving.
Once he stops moving he is more than likely to sway. The swaying is further exaggerated by unclear vision or darkness. This is precisely why it is beyond reasonable doubt that OP could have targeted his shots to the head, or indeed anywhere, from where the PT were claiming. He either had to be leaning back for stability, or swaying.
The following link makes quite interesting reading :-
link