First thing is you need to either level the tops of the cakes off, or ice along the edge of the cake board, so your icing is straight up and down, and also level.it off across the top, NOT to the shape of the cake itself. But before that, use a stiffer consistency of butter cream for a dam so that very prominent bulging doesn't occur. Maybe forget the fondant on this one all together until you can put a cake together better. Not trying to discourage you, but this is not even remotely close to what a tier of cake should look like. A beginner on their first or second cake maybe, but not someone making wedding cakes.