If you have taken a total of 90 mg worth of Adderall/XR, the best advice that I could give you would be to "enjoy the ride."
OR GO TO THE HOSPITAL! If you've overdosed, you will know. Symptoms of an overdose include, but are not limited to: profuse sweating, vomiting, hallucinations. If you think you've taken too much, call a poison control hotline immediately. They will be more capable of helping you than some random dude on the internet. Don't take this lightly, Adderall can be dangerous in high doses.