Is IPv6 working for me or not?

Regarding the OP question, I did some reading of old posts and the short answer seems to be that you cannot stop the clients IPV6 queries but if your not using IPV6 then no harm no foul as the device can't make use of the information given. There seems to be some ways to hide that information from being displayed on the stats page if really wanted to. I would suggest going through this old thread for info.

What you observe is perfectly normal.

Disabling IPv6 won't stop client software from requesting type AAAA records. e.g. nslookup would commonly send both type A and AAAA queries for a given domain.

It's also not unexpected to see a client use its link-local IPv6 address (range fe80::/10), even if the router wouldn't advertise a public IPv6 prefix (range 2000::/3) because it has no public IPv6 connectivity.