"I’m aware some people think the original version didn’t specify his size"
Well, he was a hobbit once, right? So a 10 meters tall Gollum makes less sense than a Gollum that has about the same size as other hobbits, give or take.
That's a retcon. There was no indication that he was a hobbit in The Hobbit (and as others have mentioned, in the original there was no physical description at all.)
But that's only known if you read other material, it's not in The Hobbit.