Within psychiatry, how is homosexuality discussed or classified? I acknowledge the fact that we currently don't understand the causes of homosexuality nearly well enough, but I have read about the following points:


That homosexuality may not be a choice and could have genetic grounds (different studies and views presented in this article).
That it may be a result of a traumatic experience (as this article suggests).


Without intentional cause of offense, based on these I am under the impression that homosexuality could potentially be a mental disorder.

Within psychiatry, how is homosexuality discussed or classified?
In 1973, the American Psychiatric Association (APA) removed the diagnosis of “homosexuality” from the second edition of its Diagnostic and Statistical Manual (DSM) (Jack Drescher, 2015).

Theories of pathology which declared that some internal defect or external pathogenic agent causes homosexuality, have been rejected, such as the theories of immaturity which considered the homosexuality a "developmental arrest".

It is rare to find a theory of homosexuality that does not draw upon gender beliefs that contain implicit cultural ideas about the “essential” qualities of men and women. 
Who is a real man? Who is a real woman? 
Since there weren't scientific evidences to claim: "Homosexuality is a mental disorder", after a vote, Homosexuality has been depathologized.

Accordingly, the answer to your question is no. Homosexuality is not a mental disorder, it's just a normal sexual orientation.

For further informations i suggest: "Out of DSM: Depathologizing Homosexuality" (Jack Drescher) 2015 : LINK: 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4695779/