And if the other team has a Pyro you're pretty much useless.
this just in: rockets have a blast radius that is actually pretty expansive
you don't have to shoot directly at the pyro, because that's literally Self Delete. just shoot in his general direction or towards a wall or the ground in front of him so he still gets damaged, and, even if he reflects it, the awkward positioning of the rocket makes it hard to aim it back at you
attacking from above helps, but be sure that the pyro isn't aware of you or your ass is getting juggled