From the pictures I would say it is a Bredli, because they have rather a black, brown and beige to orangish colour, whereas the Murray Darling pythons are rather black and white. I own both species and now even a third one (Womas), and I will ask a difficult question on this forum in a moment which might interest you, too (about crossing different types of pythons), but first I wanted to answer your question. So yes, in my opinion yours is more Bredli than MD.
As to the size: Both my Bredlis as well as my MDs are 8 years old, about 10 feet long and about 8 kg in weight, males and females equally. But I recently bought a breeding pair of Womas who had been kept together in the same enclosure, both 4 years old, but with the girl being about 4 times bigger than the boy! The male is only the size of my yearling Bredli girl which I have raised (she is celebrating her first birthday this month and is our very first reptile breeding success). I have my assumptions why he stayed so small while his girl-friend developed normally, but that is another story. Despite the difference in size the female has laid eggs his year and baby snakes have hatched, so the previous owner (but none survived).