Hello Shunshun,
Speaking as a former commercial diver, I have to agree with many of the responses I have seen here; especially ShakaZulu and Mislav. First off, a disclaimer: I left the business over 30 years ago, so keep that in mind when you read my post. I think there are a few commercial divers who post here, better get their fresh take.
You may think (as I did) that you love diving so much that you want to be a commercial diver. Great, nothing wrong with that. But don't think it will be anything like you have experienced as a sport diver. Still OK? Now, decide if you will like to live offshore or away from home for long periods of time. Do you have a wife, family, sweetheart, pet, car, anyone or anything you can't leave behind? I know there are jobs in commercial diving that will keep you inshore, but for the most part the money and work is offshore. Try to get a job working offshore and see how you like it. Remember, unlike the guys who work two weeks on, two weeks off, you may be on the job for a month, two months…who knows how long.
If after you have honestly answered that you can live with these restrictions, go for it. (I think I remember) you said your dad is an experienced welder. Have him teach you everything he can about welding, cutting, etc. It will come in handy not just in school, but on your resume.
Good luck and keep us posted.
couv