Sounds like too much filling to me. Are you talking about when you stack 2 cakes.. or when you put the next layer in a single tiered cake? Also.. is the BC you make your dam with stiff enough? Your filling layers shouldn't be more than 1/4 of an inch.. especially with looser fillings. Do you use instant puddings? You can try adding less milk to make it thicker. If you make it from scratch then you can add a little extra cornstarch or an extra egg yolk.
This is what I use. Apologies in advance, I dont remrmber where I came across this info, wish I could give some credit!
Gourmet fillings ready to use as filling in your cakes.
STORING: Store in the refrigerator after opening. An opened tube will keep 6 months in the refrigerator. I usually tie the end off with a rubber band and then put them in Tupperware. Some ladies have frozen them with success.
Amount of Pastry Filling Needed - This is the approximate amount of filling needed. Different fillings may vary slightly. Heart shaped cakes may take a little less filling than rounds, square shaped cakes may take a little more than rounds. One sleeve of filling equals 3 cups.
Rounds
5" 1/4 cup
6" 1/3 cup
7" 2/3 cup
8" 3/4 cup
9" 1 cup
10" 1 1/4 cup
11" 1 1/2 cup
12" 1 3/4 cup
14" 2 1/3 cup
16" 3 2/3 cups
18" 5 2/3 cups
Sheet Cakes
9 x 13 1 1/2 cup
10 x 15 2 cups
12 x 18 3 1/3 cup
Quote by @%username% on %date%
%body%