If its selected in the nvidia ontrol panel to use only the GTX765M, then its most likey using the GTX765M even though the game itself only detects the intel 4600. Due to the state of the game on laptop drivers atm (nvidia is working on a good ffarr driver fr both desktop a well as laptop) looking at your fps, its already using the GX765M. If you want even etter performance you can always go in the nvidia control panel and change soe settings like the quality of several settings to improve the fps even more.
No matter what people will say, in my opinion the hd4600 will never reach that fps with any players near.

Do NOT rely on the benchmark... the benchmark is more made for desktop gpu's and drivers, ive got a 3.3-3.7 hz cpu and a GTX680M (which is slightly overclocked .. still always on low temp. so no throttling)
.. the benchmark gave me a score of around 10k at maximal settings, meaning i should be able to have reasonable fps on medium-max settings.
But while ive got up to 90 fps in empty zones, at cities for example a laggy feeling exsists and the fps goes al the way own to 40 XD .. and that on the lowest settings possible (though always at the 1902*1080 resolution.. anything lower just fucks up the eyes ;P)