So I've fairly new. I've made about 6 cakes now and each time the cake starts to bulge out after the fondant is applied I need help, but I'll start from the beginning.

My cakes are slightly not leveled once stacked, even though I use a cake leveler from Wilton also I pipe on the BC so it can be totally even. Then they are straight up or down, I'm not sure why since I only have 1 of each pan size so if I want a 2 layer I wash and reuse the same pan and once my cakes are stacked with BC the cakes most of the time do not align. I crumb coat which seems to be the easiest part because I can just add BC to make my cakes look all even everywhere top, bottom, sides. I then add another coat of thin BC then I set it in the freezer for about 10-20 minutes then I apply fondant. Everything is fine and then a couple hours later there are bulges and BC is spilling out of the cake. I need help pretty please. I've been getting asked to do more cakes and these errors makes me not want to even bake because I put a ton of stress on myself to have everything perfect

This subject has been covered over and over again but it sounds like you're adding way too much filling and it's squishing out at the sides under the fondant.  Try using a stiffer buttercream dam around the edge, but about a half inch in from the edge so that when the top is applied it doesn't squish out the sides.  Then try not to fill the center of the dam quite so full.  This should help.  All the best to you.

Okay I'll try that, thank you :)
 

Do you let the cake settle after crumbcoating and before putting on fondant? I know some people rest a slightly weighted object on it before fondant, just to let it get used to the weight.