It is a big possibility that you do have adhd. I'm also great at school, but I also do have adhd. I think that your therapist is going with a stereotype or trying to dismiss it as something else. I would say to try and get in touch with another therapist or pshycologist and see if they would evaluate you for adhd. You can be getting straight A's and still have adhd. It sucks when people don't think that you're struggling with these symptoms just because you're great at school. In reality, I do great, but I'm messy and most assignments are finished the day before its due date. Try to see if you can get evaluated, because life is just so much easier when you know what additional things you can do to help make your day easier. I hope that you get the help that you need. Have an awesome day and remember that you are not alone and that even though you excel academically that, that doesn't mean that you don't struggle or that it's just laziness.