It's also important to differentiate feeling nothing at all, and feeling cloudy-headed and tired, they are technically different things. It certainly sounds like it's not "high percentage" at all. Even in divided doses, 100+mg should have you barely able to sit still and very likely either feeling like a God incarnate or like you're going to have a heart attack.
If you have the time and equipment to do so, you can purify street amphetamine with an acid/base extraction.
Dissolve crude amph paste in water, add enough lye or lye solution to get pH > 11,
Extract with one of: naptha, heptane, hexanes, dichloromethane, ethyl acetate, ether, toluene, etc, (you need a solvent that doesnt dissolve in water, add it to the paste you dissolved earlier and really mix it well)
Seperate the solvent off, put the water aside, it is corrosive waste that should be poured down a drain that needs cleaning... the solvent has your free base amphetamine now.
Add e.g. aqueous concentrated HCl (or sulfuric/phosphoric/citric... whatever) with vigorous mixing to the organic solvent until you have an aqueous solution which is just acidic to litmus, this way you extract all the free base amphetamine into the water layer as a hydrochloride salt, then you can seperate the water layer off (discard the solvent layer) & boil it gently to dryness (do this in a well ventilated area, if you use HCl there will be fuming if you used an excess of acid) to yield crystals of pure amphetamine plus whatever other alkaloid contaminants there may be... ephedrine etc)
Or you can recrystallize your stuff, you could even try recrystallizing it from boiling water, I'm not sure how well that might work. Look online for recrystallization procedures.
If you don't have access to solvents or glassware to do this in, you can always try washing your amphetamine with dry acetone, that can dissolve some added cuts and other stuff, but it doesn't always work with everything.
Also, if what you were sold is a wet paste, ignore what your dealer might say, and let it dry out as much as you can. Amphetamine sulphate should be a crystal or microcrystalline powder, any "wetting" is caused by water or alcohol added as bulking agents. If you remove the water weight it will make your speed more potent per milligram.