Like Christopher said, Welcome to the forums! I'm fairly new here myself.
It's good you've got a name to put to how your mind works, but it is not the be-all and end-all, nor should those labels define you (plus the doctors may not have all the facts or be accurate in their diagnosis). Like Christopher, I've experienced depression but not schizophrenia (well, sorta), however, like you, I've also got no friends and nobody to talk to, which has been my current state of affairs for about 3-4 years now. Humans are social creatures; we need social interaction, and especially someone to talk that we can share our thoughts and feelings with. It's not easy when there's nobody around to listen to you or that understands. But it's also not the end of the world (don't you hate it when someone says that?).
Many years ago I too got put into the hospital, not for trying to kill myself, but because I had a nasty reaction to an overdose of psychiatric drugs (antipsychotics mainly) which caused me to hallucinate, which ironically they gave me antipsychotics to treat my antipsychotic induced hallucinations. I've also had other experiences of seeing things that were not physically there, however those would have been closer to a 'vision' (not the right description but the closest I can come up with). So I've had both hallucinations (drug-induced) and had perceptual experiences of things not physically there but were real all the same (I was conscious when they happened). Oh, I should also mention I study psychology, so I've got personal experiences and I've also got research and study materials.
With regards to the depression, socialization and activity are the most effective. Socializing, however, can be difficult if you have no friends (my biggest problem). So you should try for some activity/exercise. You don't need to go to the gym, but exercise does help. Even if you just do some pushups or situps at home, it still helps. To begin with you may not be bothered, but push yourself a little bit and you should feel a difference.
As for the hearing voices and seeing things that aren't there, well, there could be a number of reasons for that, and it's not a 'disease' or 'chemical imbalance'. It depends on what the voices say, and when they say it. And it depends on what you see. You weren't overly descriptive in your introduction so I can only guess at possible explanations. Did something happen to you? In childhood or in your teen/adult years? Seeing or hearing things that "aren't there" can be linked to trauma or abuse. I've read an article by a psychologist who herself was abused as a child, and her voices take on several persona's, including that of her abusers, a protector/mother figure, and even herself during certain age periods. Another article mentioned many religious figures who heard voices, such as Moses and Jesus. It really depends on what the voices are saying, why, and when. They are clues to help you understand why you experience what you experience.
You've got the first clues into understanding your own mind, and you've made the first steps. Do not worry about what anyone else thinks of you. It's your mind, your experiences, and you need to understand why you see/hear what you see/hear. And by extension, do not accept a label as the reason why you experience what you experience. Imagine feeling pain and being labeled with a 'pain disorder'. Pain may be what you experience, but it is not why you experience it. There could be any number of reasons, such as a headache, broken bone, burn, laceration, etc. A label such as depression or schizophrenia is useful to describe what you are feeling, but it does not define why you are feeling it, and it does not define you.
Hope this helps.