K, I'm leaning to your gameplay being vastly different from everyone else's right here. Are you using an essential companion and purely staying in stealth, and using archery/dual cast destruction and restealthing? Because otherwise the math is baffling me.
100 Health not near armor capped means you're in one-shot category from an awful lot of 40+ enemies. Draugr Deathlord and Death Overlord archers will absolutely gib you, and its not always easy to tell when they've come in line of sight. Ancient Dragons will one-shot with power attack, and normal attack could be close depending on your armor. Without impressive magic resistance you're in trouble if they make 3 passes with breath before landing. Big Forsaken encampments with dual wielding briarhearts and and ravagers, supported by archers with decent bows (has happened twice so far) can get brutal quick. And that's with armor cap and 600-ish health. I don't use companions or summons on that char, but still you're describing someone who dies in one hit, which may be your playstyle. But that's not typical to a fairly open rpg, they don't balance for that.
Most things can kill me in 1 or 2 hits...if they catch me. Archers are definitely the most dangerous opponents in the game. I have 100 Magicka. Dual-casting Flames isn't going to do me much good on level 43. I have no perks in Sneak/Archery/1H/2H/LArmor/HArmor/Destruction/Restoration, so no benefits there. My stealth attacks do 2x damage. None of my equipped items have resist magic. I use resist fire/frost/shock potions instead. I use a companion, Novice and Apprentice level summons, scrolls, potions, and shouts. I'm very good at avoiding getting hit. I hang back, use poisons, shout people off their feet and power attack spell casters with 2H and fortify potions. I use Ethereal and sprinting to avoid dragon breath (among other things). It's not hard to do. Then I hit with poison arrows or staffs. Most of my poisons are taken from fallen enemies (falmer, frost spiders) or scavenged from dungeons as I have a relatively low Alchemy. I use traps and enemy creatures if they happen to be handy. You'd be surprised what you can accomplish with no health or magicka to speak of. I die all the time, but that's okay because I'm not having fun if I'm not fighting for my life.

In any case, my playstyle shouldn't be an issue, should it? It shouldn't matter how a person plays, Master difficulty should be difficult enough that no one playing on that setting can make their character OP, no matter what they do. That's why we have lower difficulty settings, so that players who do want an OP character can have that experience. (And I've intentionally avoided OP builds.) It hardly seems fair that everybody who wants to be OP can do so without batting an eyelash (since every difficulty setting supports it), but the players who don't want to be OP but who still want to enjoy all of the items and mechanics that the game has to offer can't do so, even on the hardest difficulty setting. It's aggravating for players like me because there's no reason for it. It's a blunder arising from indifference and could easily be fixed. I can play my current character just fine on Master (though it's starting to get too easy) but that's only because I've intentionally gimped her to make her more like an ordinary person. There's no way this difficulty setting would be challenging enough (for me) to play a perked out mage, warrior, or assassin. I would have to find less logical ways to gimp them.
join the club. it's amazing and mindboggling that people actually think they have a legitimate argument when stating that the difficulty balance is fine or that there are acceptable ways around it.
i see you're doing m/h/s manipulation, as well. personally, i've been adding health exclusively at the very beginning levels, since, that's really skewed and then trying to find that right time to then start adding stamina and magic (even for non-magic characters) so that it remains difficult at later levels.
I've put every single point into Stamina (level 43, Stamina 520). Honestly, I don't think it makes a lot of difference. I thought not putting points into H/M would really gimp me, but I can outrun almost anything and powerattack enemies into oblivion (not to mention carry more gear) with high Stamina. I think all of the attributes are fairly well-balanced, it just determines how you go about combat. I sprint in and out of combat and power attack spell-casters with a 2H axe. I use my companion and low level summons (Flaming Familiar ftw, love that little hand-grenade) to distract enemies (and, when I'm lucky enough to stumble across a low-level enemy, Frenzy and Raise Zombie). It also helps to know when to use Heal Other on your companion.