Beach Bra Frustrations

It seems no matter how I tweak the pattern I cannot seem to get it right. It gets baggy at the sides where the fabric is gathered, and although it holds the bust it cannot be said to be flattering. I am trying to find a way to get the back to carry the weight of the bust, but alas, no luck. I think I'll have to give the beach bra pattern a rest and come back to it later. For now I'll see if I can turn the bra pattern from the sew along into a beach bra. I think I have some iron on interfacing I can use to stiffen the cups in the stash, and I am thinking perhaps a shirred back panel. It should keep the bra in place and hopefully also look good.