I have experienced those feelings before, although they were always either towards a crush that I couldn't possibly be with, or at the beginning of a relationship when the initial stages of infatuation are kicking in. Which makes me wonder whether those flittering feelings are just that.
I think you really, truly know that you've found 'the one' after a certain amount of time being with that person, getting to know them and understanding their flaws and their virtues in equal measure. When we truly love someone we look them dead on and realise that they are perfect regardless of what they are.