I don't want to start sounding like an advert but the Nova 160 is the second smallest in a range of six bags - there are other sizes.
The Tamron you have is 8.2 cm long (according to Amazon) and there are some reviews on Amazon for the Nova 160 from folk saying that it fits their camera with 18-135mm attached - which (according to Amazon) is 10.1 cm long. Another review says " takes the Canon 550D camera with either the 18-55mm or 55-250mm lenses fitted directly onto the camera body".
The Lowepro website says
1 DSLR with lens attached (18-55mm or 17-85mm f/3.5-5.6) plus 1-2 additional lenses; 2 memory cards and a flash unit
Size(Interior):
7.9W X 4.3D X 6.7H in./
20 X 11 X 17 cm
Measure your kit and look at the internal measurements and reviews online. To get a better idea of size of ANY bag that you're considering, if you can't get to a shop and see one in the flesh, try doing a google video search - here's
some Nova 160 videos
I have a toploader zoom 2 (old model) which I sometimes use with a shoulder-strap, sometimes on a S+F belt with a couple of lens pouches (one of which houses my flash).