Help me understand the Mind of an addict/alcoholic(me)?

Why is it that I was once addicted to Crystal meth and AM close to overcoming my addiction. By that i mean I do crave it but I don’t look for it I don’t try to find it yet, if there is a “tweeker” in the room I CANNOT be in the same room I must leave I can spot them a mile away. It gives me the jitters and I refuse to touch that drug.

Then I tried alcohol (which took me a while because my father wasn an alcoholic and I refused to drink even though I was tweeking) and I was like STUCK I WANTED more and more. Now i can go on for MONTHS at a time without alcohol BUT when I start drinking I just want more and more I can’t stop.. I was never like this with my previous addiction..I just can’t figure it out..