I always had a problem with bulging until I switched to the ganaching method. I put a ganache dam on the perimiter of each later and chill that till hard, then I fill the dam with my filling of choice just until it is flush with the dam, then place the next layer on that and proceed until the cake is stacked. Then I chill the whole cake in freezer for 10 minutes and then ganache the entire cake and smooth smooth smooth until it is perfect like glass – I finish it with boiling water and pastry brush to get it absolutely flawless (the fondant will show everything and accentuate the flaws rather than hide them). I let the cake sit out overnight (or chill depending on the perishability of the frosting) and cover it in fondant the next day. I’ve never had a bulging problem since I switched to this method. there are tons of tutorials on line about it. good luck.