i baked a sheet cake last night, i am only doing one layer, but for some reason the cake didnt rise as much as it usually does! i used a 2" pan and the cake is about 1 1/3" thick! is this too thin to use for the sheet cake? i was only planning on doing one layer!

In my opinion, it it way too thin. A single layer cake is generally expected to be closer to 2" high.

I would bake another layer

JoAnnB's right. It really should be 2" tall. Just bake another and fill with bc.

I would be concerned w/how it will taste since it didn't rise.
Did you put enough batter in or did it just not rise right? What caused that problme? Did you put all the right ingredients in?
What is the cake for - a personal occasion OR a customer?
I'd sure start over so you have a good cake.
Keep the thin layer for your family OR cut it & stack when you need a smaller size.