Adhd symptoms

Okay so I’m a 26 F and I’ve recently been diagnosed with ADHD (officially by a doctor). I’ve been taking amphetamine salts & my dosage have been raised 3 times. First 15mg then it was 25mg now it’s at 40mg. I’ve been having a hard time trying to understand what it is that I’m supposed to be experiencing while taking the meds and what I’m not supposed to experience. When I first was on 15mg I realized it didn’t work after the first few days. Then when I took the 25mg I had orientation for my LPN program one of the days I took it and I wasn’t able to fully focused on what the teacher said. I felt myself “daydreaming” a couple throughout the session. So I called my doctor back to let him know what happened so now I’m at 40mg. Since I’ve been taking that (2 days) I’ve been shaking a little, my dad said that I stuttering bad yesterday and the stuttering slowed down a little today but I sometimes forget what I was trying to say when I stop talking for whatever reason. And I’m at the point where I’m concerned because I know it’s supposed to help me focus but it doesn’t seem like I’m really able to especially with the stuff I deal with in the process of taking it. idk what to do and it’s making me feel discouraged cause it doesn’t seem like it working and I know I need the help. 😩please give me any advice about it. This is my very first time taking medication for it and I also have anxiety.