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I can't say that I know what you are talking about or what things that you are going through that are permanent, but I am sorry that you are going through this. I won't say that time will fix it, because I don't know what's going on and I understand some things are out of your control.
Is there anything you can do that will give you purpose or fulfillment? For example, if you like art, maybe put time and effort into your craft. Or, you can volunteer somewhere where you can be proud of yourself for making a difference.
Sometimes you have to let the small things make you happy as well. They can keep you going for a while until the big things come along. It can even be something simple like hot cocoa and your favorite blanket, watching the rain fall, or baking your favorite goodie.
You're right that it sucks when friends don't notice you're withdrawing. Sometimes friends also worry that they will be bothering you if you ask about it. Others are the type of people who don't reach out first or expect someone else to reach out. Others get caught up in their own lives and things fall by the wayside. There are tons of reasons why they may not be reaching out, but I think it's something you should talk to them about. You don't have to say "you're not reaching out to me so I'm upset," but you can say that you feel neglected or left out right now and are having a hard time. Ask them to take the initiative or check in sometimes, because they may not have even realized. Even just ask a friend to go get a coffee and talk things through. I know taking the initiative is hard and feels like it defeats the purpose, but sometimes friends genuinely don't pick up on the signs that someone is struggling.
Do you have a therapist you can talk to, or can you get one? They can really help because they're not there to judge you and won't blame you for having permanent things going on that are out of your control. But what they can do is offer suggestions on how to cope and ways to build a life worth living. You don't even have to go on medication if you don't want to.
TH has a safety zone located here. If you click "currently in crisis" it will give you pages like hotlines, alternatives and coping methods you can use, and other resources.
I hope this helps at least a little. I just wanted you to know that we care.