Whenever I use "I should've done _____", I like to add an extra part to the sentence looking for confirmation as in "I know, right?", where "right?" is the part asking for confirmation.
My question here is: What is the most natural way to ask for confirmation after "I should have ..."?
I should've gone to the store sooner, shouldn't've I?
I've been using "shouldn't've I?" but my girlfriend argues that that sounds weird, which it probably does. She argues that it should be "shouldn't I have?"
What tag question should I use?