Back fat = scoop more! :)
Because I literally don't have any gap between my boobs the central gore always sits slightly on boob rather than between, even with my Ewas. When I lie down (braless) there is still an ever so slightly fleshy section where the central gore would be. It's not to the extent that you would look at me and go "monoboob" but I think that because of this I will always have some marks from a central gore. For me, the most painful bra is actually a plunge - my "non-gap" goes the whole way down so the end of a plunge actually digs in which hurts like buggery sometimes. A bit of a forced gap hurts me less
If you do actually have a gap low down then a plunge might work.
If the (bad) description of my non-gap sounds familiar then another bra I like is the Bravissimo Betsy Bow. It's similar to the Alana, but it runs small in the back so where a 30 Alana is feeling a little loose the 30 might fit in this one.
The baggyness at the lace section is a tricky one and is more a style issue. I've suffered from it myself in the past as to get a bra which didn't hurt in the middle I needed something quite tall, but if this had enough space for my boobs at the bottom I'd have a wee bit of space at the top. But a size down - quad boob! 
Sorry that may have confused you more!