First... is that the Freya Deco? How do you like it? I'm trying to get my hands on one as we speak...
It looks to me like some of your breast tissue has migrated under your arm, possibly due to bad bras in the past. It sounds crazy, but if you wear a bra with higher sides temporarily, and firmly scoop all the extra tissue under your arm into the cups, it will rejoin the rest of your boobs after about a month or so. I used to have that same bulge, and it has almost entirely disappeared -- and I went up almost a cup size in the process. There's a good post about it at this wonderful blog, Venusian Glow http://venusianglow.blogspot.c.....conds.html (she calls it the breasts "returning to the motherland", lol) and, for those of you who read Polish, The Bra Lobby is apparently full of stories of women who have seen this happen when wearing the right size.
P.s. After looking at it again, I wonder if the underwire itself isn't wide enough for you. Does it extend far enough back under your arm to support all your breast tissue, or is the wire kind of cutting into the side of your boob? If it is, don't despair, some brands are made to fit wider breasts than others. You shouldn't need to change your band size regardless.