On long haul I always press the button if I want another drink unless I particularly want to stretch my legs. Short haul I wait for a FA to be passing

Once meal service is out of the way the FAs aren't busy. At that time, I regard the plane as a flying restaurant. If I want another drink in a restaurant I don't go to the bar to get one, I ask a waiter to come over and take my drink order and the plane feels the same

So long as you're polite there should be no need for embarrassment, that's what the FA are there for (amongst other things, naturally)

nickyboy