Is these sentences are correct.

Debbie felt nervous and out-of-place at the party so she sat by herself at the end of the sofa.
She didn’t want people to feel sorry for her so she kept a strained smile on her face.

2 answers

Again, you have written two sentences instead of one, and neither is a compound-complex sentence. Are you clear on the meaning of "compound-complex"?

My question is this: Do you have to combine those original 4 into 1 long sentence? Or is it OK to combine the 4 so they make up 2 sentences?
These are also fine, given the instructions you posted above.