it really isn't a potter/sw cross if the only thing you use from the potter series is the main characters name and description, you should try throwing in some basic magic use have him do something wandless when he is backed into a corner then expand his abilities from there, it doesnt have to be grandiose simple stunner, shields and expeliarmous would work fine.
also you need to work on your battle strategy a bit, everything harry did was blindingly obvious and basic, surround them (which would spread out his men to far), use there captured guns against them (who wouldn't)and then he the leader plus a small group somehow sneak into the midst of the enemy leadership undetected and kill them all (highly improbable to work as well as foolish, big difference between being near the front lines and being on a suicide mission) as the writer you control both sides of the battle so set up a slightly more intricate trap next time, its better reading and as the writer you can make sure that hary's plan always works be adventurous