Asia A. had an article on this topic sa FHM recently. All you have mentioned are actually tell-tale signs that you lady have cummed!!!
. However, its not guaranteed. Why? in as much as you can have a pathological liar which even a trained professional or polygraph machine would never catch to be lying, there can be women who can trick you to believing that she reached the Big "O".
You can see the physical manifestation but as they say, what you see might not necessarily be real. You might hear it but a "good actress" can emote her way to your pants. Even touching, tasting nor smelling it is not an assurance. Besides, each lady has her way of manifesting her Big "O" with some not even able to reach it.
Just my 2 cents worth!!!