Clinical depression is very specific, low mood + low energy + anhedonia (unable to find things pleasurable) for over 2 weeks.
it is indeed a chemical imbalance in the brain, its mechanical, like not having enough air mixed into the fuel when your engine is running, the car wont function at 100%. There is no blame, no stigma, you have no control over this imbalance. Anyone that has a 'pull yourself together' attitude is ignorant of the underlying physiology. Who would say such a thing to someone with a broken leg?
Depression is real and it is hard for people to cope with. Doing activities that you enjoy will help, it will release more of the good chemicals into your brain and help counter the current imbalance. The problem is, be definition with depression, you,don't want to do the things you enjoy and you don't enjoy them as much.
So very briefly, in your brain you have happy chemicals (serotonin 5HT, adrenaline) and you have doors that let them out the brain (receptors). The antidepressants close the door on these chemicals so they can't leave, they build up to normal levels. Depression itself can be a physical malfunction of these 'doors' or the production of happy chemicals.
SSRIS (selective seretonin reuptake inhibitor) are first line therapy, fluoxetine (Prozac) citalopram, escitalopram.... These have minimal side effects of nausea, vomiting etc for some people. They work for many people. Though they take at least 6 weeks to work, because once they close that door, it takes that long to build up the good chemicals. So give it time. Of course, doing activities you enjoy whilst on the drugs will help you get back on track.
Alll the best and stay strong, there is light at the end of the depression tunnel! It's a physical imbalance, there is a physical solution.
snare x (ps just a trainee doctor, not a doctor)