It would be pretty hard to argue she's not AB, from the lyrics of her songs, to the fashion accessories, to the way she dresses and uses samples like baby pianos and music boxes in her tracks... one could almost say she helps to make AB more mainstream.
As far as her being a DL? I haven't seen anything to support that like I have Miley Cyrus, who not only took pics of herself wearing diapers with the second-chance blue & white tapes visible (so you could definitively say it was a diaper and not just puffy underwear) but also admitted in an interview that acting like a baby was "creepily hot" to her. Not the best press for us though, haha.