Some things about depression:
There isn't an answer on how to cure depression.
There is no regulatory body for professional psychologists. You yourself could set up shop as one tomorrow if you so pleased.
Every single theory to do with the cause/cure of depression can be disproved.
The basis of many of the major psychological theories are laughable.
However it is all about what works for the individual, so don't listen to anyone suggesting you shouldn't try treatment x because it doesn't work. It doesn't matter if it doesn't work for 99% of people, if you are in the 1% you are clear, happy, free and how good would that be ?
Some psychologists believe that all we are are chemicals and hormones, which may be true. In which case load up on pills to sort out that and you're fine.
There is the danger however that doctors can tend to dispense the pills to cover up the problem rather than fix it.
Others believe it's more about the mind(whatever that is) and this could just as equally be true. In which case you could do with seeing a psychologist. If you are going to, do your research and get one who is qualified with a degree from a decent uni. I'd advise going for a cognitive psychologist, and avoiding anyone who follows the psychodynamic approach. That is of course just my opinion and as I said you should ignore opinion
One thing I really strongly recommend no matter what path you choose is exercise. A good work out relieves stress and releases a good dose of the chemical into your brain that makes you feel good after sex, smoking weed or eating chocolate. The making and achieving of goals gives your life structure and achievement. As such exercise covers both the biological and cognitive approaches - guaranteed success !
If it helps, look at the stars on a clear night sky, think about how big the universe is and how small you really are. What's the point of worrying when you are so small ? Relax and enjoy life - why not ?
Good luck pal, if you do do some research and end up struggling with some of the concepts give me a shout