As someone who has been a lead teacher in toddler room:
Everyone below is correct. We often see more parallel play at this age. Some children may look like they are 'playing with' others, but it's usually a shared interest that they are gathered around, such as a sand table or cars or blocks. It will take a while before kids this age learn to take turns (the first step in 'sharing') and navigate the social work of group play.
It's also worthwhile to rethink the idea of what 'fun' looks like. For younger children, play is their work. My son is five and at all ages, when he's having a lot of what he would call 'fun', he looks very intent and purposeful at what he's doing. When he's concentrating, he's not really smiling or expressing happiness, he's thinking about what's going on right in front of him. Some kids are more active, busy learners; girls are likely to be a little more relational/social than boys at this age too. Some kids are fly-by-the-seat-of-their-pants joyful and flit from activity to activity and some have a more solemn demeanor.
Do what Wickerparkgirl suggested and ask specific questions. One thing I would also encourage you to remember is that we teachers often use the term 'friends' a bit euphemistically. There is sometimes a degree of affection between children, but when we say that children are having fun with their friends, we might also mean that we had a great time doing some music and movement activities and playing in close proximity with each other in the sandbox. Keeping in mind that sharing space is a real challenge for many kids, it sounds like you are getting some positive feedback.
One more thing to add: you are meeting with the director, but she is not in the room with the toddlers. Any chance you could get a phone conversation in with the lead teacher before then? I only ask this because as someone who's been in that position, I would wonder why the parent wasn't asking me first. The teacher is going to have better knowledge of your son's day. At the day-cares I have worked at, the directors were more or less peripheral figures when it came to the child. I suggest scheduling a time to talk on the phone because then the teacher can give you her full attention instead of short "this was a fine day" information. As a toddler/preschool teacher, I would appreciate parents coming to me with their concerns first, and then if an issue was more complex and harder to resolve, for all of us to work as a team with the director's guidance.
Good luck!