Ok, that's good!
Adderall is a combination of four amphetamines. Your dog weighs 12lbs, which is 5.45kg. So, she ate a dose of 0.55mg/kg of this combination.
At about 0.5 mg/kg, we expect to see mild signs of amphetamine toxicity (agitation, hyperactivity, rapid heart rate, panting, muscle tremours). At doses of about 2-3 mg/kg more serious signs start to be seen.
So, without you inducing vomiting, your dog could certainly have had toxic effects from this!!
I would now recommend that you give her ACTIVATED CHARCOAL.
In Canada you can buy it in the local pharmacy and I expect you can in the USA as well. It is widely used in human and veterinary medicine to bind up any toxins that have been ingested. The dosage for activated charcoal (all forms whether capsule or suspension) is 1-3 grams per kilogram of body weight. Thus, for a dog of this size, you should give 6 to 18grams.
Here are some links about activated charcoal:
In general, getting the dog to vomit and then giving activated charcoal is useful. Since this Adderall formulation is extended release, then repeating the charcoal in 4-6 hours is also indicated.
Most dogs will readily eat it in a bit of baby food or cooked rice, or non-fat cottage cheese. If you get baby food, check that there are NO onions or garlic in it (as these are toxic to dogs which would kind of defeat the purpose...!).
Then, if your dog has any problems, symptomatic treatment would be indicated (which just means treating the symptoms).
A veterinarian can give acepromazine or chlorpromazine to counteract the effects. Also, a vet can give cyproheptadine (Periactin) orally or rectally dissolved in saline, which may be helpful. The cyproheptadine can be repeated every 4-6 hours as needed (to help with the extended release part).
Symptoms usually start within 1-2 hours of ingestion.
Here is more about it: http://www.petplace.com/dogs/amphetamine-toxicity/page1.aspx
If your dog is showing any of the above symptoms of agitation, hyperactivity, rapid heart rate, panting, muscle tremours, then I would strongly recommend that you take her to a veterinarian immediately for treatment!
The above is given for information only. Although I am a licensed veterinarian, I cannot legally prescribe medicines or diagnose your pet's condition without performing a physical exam. If you have concerns about your pet I would strongly advise contacting your regular veterinarian.
Best wishes, Fiona