How can I help my very unwell sister?
Recently, I've been getting worried for my sister. We're both teenagers, although my sister is older. My sister has been diagnosed with Depression, OCD, and Generalized Anxiety Disorder. I won't go in detail, but my sister has been SH for I assume two years now. I even remember taking a blade I found in her room and throwing it out a LONG time ago. However, my parents only confronted her a few months ago. She said she'd stop, but just yesterday my mom found her doing it again.
The thing is, helping her seems to just not work. My parents have taken her to therapy for over a year, but no progress was made and she stopped going just a few weeks ago. Even though they know that she's still needs helps, they've stopped trying to help it seems. Me and my sister are close, to the point where I'm her only friend, and she's able to open up to me. She's very vague, but she tells me that it's never gotten better and instead gotten way worse. This doesn't mean she doesn't shut down around me though, she'll only tell me vague things and keep the rest to herself, so it's hard to know what she's really feeling. My family doesn't want to put her on medication, because they're worried about the side effects or something.
Also, because of her OCD I think?, she tells me that she gets bad intrusive thoughts and she fixates over negative things for days straight. It makes me a bit confused on why she feels this way, because she lives a pretty average life and she's homeschooled, so it's not like she's getting bullied or anything. She doesn't interact with anyone online either.
So, because it's pretty much only up to me to make her feel at least a little bit better, I'd be grateful for advice on how to help her.