Even with lvl 100 and all five perks that enhance the effect of your potions, you still can't craft healing potions equivalent to a Potion of Ultimate Healing, or poisons that can work on characters from any level.

Leveling up and getting perk points.

Alchemy is one of the most powerful skills in the game. It is without question, the most versatile.

You need to sport a set of Fortify Alchemy gear and you will craft potions and poisons that will far outshine anything you can find, loot or purchase.

Google Skyrim Alchemy and you will be shown several sites devoted to making some truly incredible concoctions.