Thanks for the confirmation that 30 cm was the total length.
That makes it a sub-adult.
Males of breeding age have a distinctly swollen tail base at this time of year.
Just this arvo, I went out the back & had a close look at an adult male.
He's swollen at the tail base, but not uniformly.
When viewed from above you can see that the swelling is greatest ventrally. i.e if you had a cross section, it would be pear shaped.
The swelling is caused by the turgid hemipenes.
It's sorta hard to describe. I hope you get the idea.
It's the same for many other reptile species at this time of year.
Anyway, I hope I've helped.
Cheers, john