I politely caution some of us to not invalidate Emma's worries, and moreover, to just be mindful of the gender dynamics involved (we're talking about a woman in a vulnerable position, alone, with a male taxi driver, and men in this thread deciding second-hand that she's imagining it and nothing happened, when we as men will never quite understand what that's like. Sorry...I had to put it out there).
OK...now that I've gotten my 'elephant in the room' (thread?) out of the way - Emma, I once had drinking habits like yours and they eventually progressed into something far, far scarier. Rather than try to moderate, I'd say give sobriety a shot. You won't regret it.
ABW1