I have similar experiences. I find the Levoamphetamine in Adderall is less helpful that just pure dextroamphetamine
Adderall is a mixture of amphetamine salts, which have different chiralities (left handed vs right handed) Levoamphetamine is the left handed version and dextroamphetamine is the right handed version.
Dextro is the main one and the more active of the two. When I take formulations with levo i seem to have more side effects and headaches.