Two things I can add here:
Alcohol dependency and alcoholism are different things
Something many people don't realise about alcohol is that your body becomes dependent on it very easily... It's one of the few drugs where an addict can die from going cold turkey (the delirium tremens). Hence, why heavy long-time alkeys are given a weening period.
After a heavy sesh, much of the hangover feeling is because the alcohol is leaving the system and you are, in effect, going cold turkey. That's why the old "hair of the dog" trick often works.
So, perhaps the reason you "feel" OK the next morning isn't because you are sober, but more you have acclimatised to the alcohol in your system on this particular session?
Liver function is largely constant
A sobering fact is that whilst body mass (and hence blood volume) have a LOT to do with how much you can drink without falling over, liver function is completely unrelated.
You may be a healthy 18 stone man who can drink 4 times what your healthy 8 stone wife does, but each unit will take just as long to be processed. So, she's pi**ed on half a bottle of wine but will be sober again long before breakfast, whilst you've drunk 2 bottles of wine and won't be fully-clear until this time tomorrow!!!
I've been requested to blow into the tube just once, but got a "0mg" and green light. The policeman thought I was driving suspiciously as I started taking left and right turns as soon as he got on my tail. To be fair, I was driving home on my normal route and was 50 feet from my door when he put on the blues