Is it possible to be misdiagnosed as Aspergers but just be an shy introvert instead?

Sure, it's possible. Other disorders can sometimes resemble Asperger's symptoms. In your case, your ADHD and social anxiety might explain what seems like Asperger's. It's worth bringing up with your new therapist, at any rate. If your psychologist did not in fact do a full evaluation, that alone would merit a second, more thorough opinion.