Hi bunchie
Blackouts are very scary. Definitely do not go back to the bar to ask about that night that is pointless. Instead of beating yourself up just think about how totally irresponsible the bar staff were to serve you so much alcohol that you blacked out. Serving someone intoxicated is illegal and they failed in their duty of care to you.
I understand being a binge drinker and not drinking everyday blurring the boundaries of whether someone is an alcoholic or not.
All I do know is binge drinking is the most dangerous form of alcohol abuse and I hope you and I avoid this in the future.
Don't dwell on what might have happened concentrate on the her and now. Take care.