BTW, (regarding your topic) my advice is from my own experience and research not a medical field
I do get so called "lightheaded anxiety attacks" but I was sent to a neuro and ENT to rule out possible physical causes such as inner ear disorder or CNS disorder. Have to see them yet.
Its a good thing your MRI came back normal that pretty much rules out anything serious. But you should do some extra tests before you can label it on anxiety.
So it is most likely anxiety but you can't know for certain until you rule out other possible causes. Especially the inner-ear.
For the record, even if it a physical cause, it can't be nothing serious.