... something is wrong. I think it's the image itself, but I'm not sure. Perhaps I'm doin' wrong the blur effect? I'm using Gaussian blur with 8.0 number in it.
I presume you experimented with different radii for the Gaussian Blur, so next, why don't you try:
(a) Photoshop's "Lens Blur" filter;
(b) Photoshop's "Diffuse (anisotropic)" applied repeatedly;
(c) some of the new blur filters introduced in CC2014;
(d) download a free trial copy of the plugin,
"DoF Pro" by Rosenman;
(e) and finally, get a photographer with a full frame DSLR, about a 100 mm f/2.8 macro, and knows how to light a still life like this to show you what it could look like straight out of the camera.
I assure you that directly comparing many of the common blur / depth-of-field filters with the "real thing" (ie, an OOF lens) will be very informative.
Tom M