How did you know for certain that your child had ear infections vs fluid in the ears?

LO has been treated for 6 ear infections and we are going to see an ENT in two weeks. DH has been reading about the tube surgery and the current studies on hearing loss and speech delays associated with ear infections/ fluid build up. Except for two ear infections where LO tugged at the ear before diagnosis he doesn't show signs of irritability. Now DH isn't convinced he had ear infections at all and maybe he is just prone to drainage issues. He has had "pink eye" type drainage from his eyes, but the pediatrician said for sure it wasn't pink eye. If our pediatrician has the diagnosis wrong will the ENT know for sure?

LO's daycare teacher expressed concern he doesn't respond to his name. We have noticed this at home a bit too. He will respond to sounds, and his name after 3-4 attempts in a row. Maybe it's a delay or we use his nicknames too much. What do I need to look out for and bring up to the ENT?