How do I know if I have depression?

You go find a psychiatrist or psychologist or therapist and they will diagnose you.

You go and talk to your doctor. You get  physical, to rule out any medical issue. You also get a referral to see a mental health professional. Doctors need to diagnose you.

Some symptoms include a pronounced change in mood and behavior, social isolation, diminished interest in almost all activities, a notable change in eating habits and sleeping patterns, and intense feelings of worthlessness or unwarranted guilt.

Of course, nearly everyone has one or more of those symptoms at some time or another. But if symptoms persist for more than a couple of weeks, a physician may be able to help determine if your sadness has a medical cause.

If you do suffer from clinical depression, there is nothing to be ashamed of. With treatment, many sufferers have begun to feel better—perhaps the best they have felt in a long time!

Reading symptoms can be a bit confusing due to the varying levels  .. As one may draw the wrong conclusion.  The best way to get diagnosed is by a doctor.

if you sleep a lot .