I doubt most readers really worry about this level of detail, but this has been an interesting discussion to read.
Have you considered giving your character more than one set of wings? Dragonflies have long skinny bodies and two sets of wings. Because the lower body of a human is so heavy, it probably would need a set of wings for balance and support. I'm not sure how to fit that in, physiologically, especially if you want your person to wear clothes.
What about small wings that flutter quickly, like bees? Would it be possible to lift a human off the ground? Several sets of small wings may be more practical than one set of big wings, especially for hiding them under clothes.