Our evacuation PA is ( should have been anyway. . . )
" evacuate the aircraft using all available exits" ( rolls nice and easily off the tongue eh ? particularly in it's full form and for non native English speakers. . . Duh )
So whether overwings were used would normally depend on who was sitting at them, unless you remember a PA to the contrary. If the situation was felt to be serious enough to warrant an evacuation I can't from this distance see an obvious reason why they wouldn't have been used. Captain's call on the day, which of course he will have to justify.
If you find the time, I am sure we would still be interested to hear your version of events.