Boy puberty...help!

[Traveller]

DS1 will be nine in September and is starting to be a bit more private with his body, which is fine, so I haven't seen him naked in a few weeks as he likes to shower independently.

Tonight he stripped off naked with the other kids and was waving his bits around (as you do lol) and I noticed his right testicle is all of a sudden massive, easily twice the size of his other one. At first I thought he must have been kicked but he said no, it just happened. Dear lord, is this puberty already? And is lopsided development normal? I'm scared to Google the issue in case I end up in dodgy websites.

Just to add, he hss a puberty book because I thought this might be coming in the next year or so and ds1 is therefore quite blasé and thinks this is jyst normal, it's only me freaking out about the lopsidedness and the fact he's not even nine yet.