Yes. I am playing on hardest difficulty too, and like you, I was getting my @ass rocked all the time(I have died around 200 times). Now though, I am a more formidable killing machine.
The key is not in leveling up your character either, although that does help, obviously. The key is learning the best way to utilize what is at your disposal. So...
-Learn to effectively dodge, do not dive.
-Learn the timing of light & heavy attacks.
-Use Quen.
-Find & create the Swallow potion. This really helps in combat as it regenerates your health.
-Do not get surrounded. Use the environment, if possible, to limit how many can attack you at any given time.
-Patience. Keep that block/parry up and pick your moment to strike.
-Try to strike from behind as much as possible, it does more base damage, and maximizes critical hit chance.
For alghouls specifically, make sure you use Axxi( the mind control) on them when they show their spikes. That will force the spikes back in and make them easier to kill.