"Mama mea este un avocat."

Translation: My mother is a lawyer.

[JamesTWils]

Is there no feminine form of avocat?

[gustawsohn]

There is also the feminine form, ”avocată”, ”avocate”(in plural), but the profession is called ”avocat”, regardless of gender.

[Jeffrey136200]

Why is the "un" included in "un avocat" whereas in other examples of professions the "un" is not included?