Choose only the correct sentences

Which of these sentences are correct?

• I didn't go to school because I was ill.
• I bought a book about mythical creatures but a notebook.
• After school I went back home. Later, I talked with my friends.
• I liked the film but the popcorn was disgusting.
• We didn't catch the bus or we waited for three hours more.
• I'm good at drawing before I'm bad at swimming.
• Sally went away but I was still waiting for our mum.