Nice question! Quick rundown of characters in my WIPs, and you'll see the number changes quite often!
The Sleeping Kingdom has one main character (story told from her POV), and three other major characters. Sometimes I feel like they don't have enough screentime, but I had to get everything in under 80k. They'll get their spotlight later. This book has a large number of minor characters though. I won't bothering counting them, but at the top of my head I'd say seven or eight. Then there's also the antagonist.
Fractured, my debut novel, has one main character, an antagonist, three other major characters and about five minor characters.
Reflected, the sequel to Fractured has a lot more characters, but this tends to be normal for sequels. It has three main characters, two antagonist characters, two major characters and about five minor characters. The big change here is switching POV to three main characters.
Ghostslayer has limited characters. There's a main character and one major character, then another character who gets a bigger role toward the end. I understand your point about this feeling claustrophobic, but that's kind of the vibe I want to give with my novel anyway, so I think it's appropriate. There are a number of minor characters as well though.
Soul Thief, my last WIP has one main character, one antagonist, one major characters and a small cast of minor ones.
It varies a lot depending on what the WIP needs. Some stories are mostly plot driven or rely heavily on the main character, others need a fully-developed supportive cast. I say there's no such thing as too many characters, or not enough characters. It depends on what your work needs.