The number of nano-points I have seems to decrease without me spending them - is this a feature I wasn't told about or just that I must be dying and forgetting to pick the samples up again? I could swear It's not the latter, but I'm wondering whether there'd be any point playing through on easy when I've completed it to not die so much ergo keep my nano-points and get kick-ass upgrades...
I found that I'm getting far more nanosuit points now that I'm in the later part of the game fighting the aliens more. Although I do make a real effort to go around each corpse and pickup the sutff.
Ensure that you are killing them in places that you can get to also. I shot a few off the edge of things and into holes where I couldn't get to them. I do find that not all of them drop the cloud that you can collect. I recall replaying some sections and not getting the points.
Perhaps you are collecting the points, and then it won't let you collect the same points again, but is keeping the total? It sounds like it would need a little testing. Such as running the same section multiple times, noting how many points you got each time.
I will try and remember to look at it next time I play :D