I wouldn't call psychology a 'pseudo-science', more that it's at a level of development comparable to 19th century medicine, when the concept of infectious disease being due to transmittable microbes or viruses was not understood.

Most 'psychological disorders' today are not diagnosed based on specific physical-chemical tests, i.e. one can say with high certainty that a patient has drug-resistant tuberculosis using a PCR test. In contrast, there are no definitive tests for everything from ADHD to schizophrenia to bipolar disorder to depression, although more diagnoses lead to more pharma drug sales...