Im taking a wild guess that you are using the annihilator? Unless you are using it in combo with 3-4 guys, the anni simply isnt an effective kill weapon. Unlike the widespread myth that the anni just pwns vehicles, its actually a deterrent weapon. Or long story short: you scares vehicles away, getting zero certs, while your friends then get to kill ppl. Good for the team, bad for the player. Yep you are right nanoweave lvl 2 makes you survive one extra bullet at close range and lvl 5 makes you survive 2 ekstra bullets AND make you able to survive a bolt action head shot. I use nanoweave lvl 4(i do have a flak layout for when i have to fight vehicles), and for me its down to me not being hit very often by explosives. I perfer small-medium scale fighting where ppl dont spam explosives, but if you are in the larger fights then flak is the way to go.
Nanoweave 5 increases your health from 500 to 625. Coupled with shield, that's 1125 effective health. A headshot with a bolt action sniper rifle does 1500-1600 damage. Also like I said before, 125 health isn't going to save you from a whole bullet out of any gun except the TR default pistol or SMGs at long ranges, so whether you have 2 or 5 it's just one more in most cases.
I run with nanoweave 5 and can take head shots from any sniper rifle at range. We tested it our with the NC Longshot and the sniper had to be within about 70 meters to 1-shot me. If a sniper can get that close and manage to headshot me, he deserves the kill. As someone else mentioned earlier, I die to direct infantry fire, not including grenades or C4, more than anything else and prefer the extra health that universally increases my survivability. I've survived enough firefights with less than 1 bar of health to say I got my money's worth, so to speak.
One thing to note is that the spreadsheet says "Locational Damage - Leg shots apply a .9x multiplier to damage. Headshots cause 2x damage for most weapons, with shotguns and some special weapons dealing 1.5x on a headshot instead. Sniper rifle headshots are currently untested, but should be 1.5x." If that is the case then I wouldn't be surprised at people surviving headshots at range with nanoweave.
So uh...back on topic, I haven't taken the time to put up any videos of infantry fights as a heavy, but I know I have some that would give a good idea of my play style. The thing is, and I'm assuming OP played a VS heavy, that NC heavies play completely different than VS heavies due to the types of weapons available to them, so seeing my gameplay probably wouldn't be very helpful.
I play two classes, my main is an HA and I play a Medic when I can. I am horrible, I have calculated it out to a point where I typically die 2.5 times a minute using my HA. In a typical 3 hour play time I will get around 100 deaths. My K/D bounces between .5 and .3 most of the time. I am owned by everything and everyone in this game it seems yet people tend to tell me that my stats are better then I give them credit. Personally I hate failing and these number I have just spoke of is greater then failure. Personally I do not know what I am missing. I cant understand how others see me and how they seem to hit me with precision from great distances and not playing a the infiltrator. Hell just the other night I had this infiltrator make me his bi#%! 3 times using an SMG and taking me out from 100m. I wish I knew how. I seem to have trouble seeing others and if I do see them, hitting them is a real chore. I could easily blame my graphics but running a $1500 desktop doesnt give me much room to ***** about my hardware. So that isnt the issue. My outfit dreads at times when I log on because I spend more time on my back dead then supporting them in the firefights we get into. That is by no means to say they are a bad outfit but to simply point out that I certainly am not pulling my weight. I have tried different play styles; running into fights is the worst but taking my time and being patient and cunning seems to get me killed almost as often as just running in guns blazing. If my character had all the damage saved to his poor body, his back would be nonexistent from the number of times I have been burned down from behind. There are a couple of TR guys out there the love me to death as I have given them more certs then I could ever gain in a full night of play. So to the OP, if you think you are bad or think your stats are no good, trust me buddy, you are not me. I would be prideful in the success you seem to have at this point and keep at it. It could be worse, you could get the curse of the suck like I have. Knarfis