Should 'This is my job' not be accepted?
Not sure, I think no. Maybe "occupation" could be an alternative. But profession and job are different things. My profession is an artist and my job is a birthday card designer. Job = робота (~= work)
I see what you're getting at. The job is what one does within the profession?
Mm, I think so! Profession is what you are and job is what you do :)
"Occupation" should be accepted though
"It's my proffesion" Why is it wrong?
I still think this is my job should be accepted. This is my work should not be accepted, but this is my job, yes. Few english speakers would say this is my profession.
Yes, anyone who said "This is my profession" would sound pretentious.