> One shot of vodka in a standard-breakfast-sized glass of orange juice.

So about 1.5 fluid ounces of 40% strength vodka mixed with about 4 of orange juice; a little more alcohol than a regular beer at more than twice the strength.

I think your evident belief you weren't drinking something twice the strength of beer proves my point entirely. And you may well have made the sensible decision to have stopped all that, but I assume at the time the notion of doubles, shots, "on the rocks" or with "just a dash" of cola or lemonade weren't alien to you or more moderate drinkers either. The one thing I can safely say I haven't done with spirits is carefully mix them down to 4-5%