Sister with Depression

Hello there I'm new here but I need an outsiders view someone who can tell me what to expect.

My sister age 22 broke down last Monday and confessed that she hasn't been working on her degree in college, she was meant to Graduate this June but apparently it was all too much for her and she couldn't cope with it. She hasn't attended college since October last year and has been lying saying the lecterns have been canceled or been going to school then coming home. A lot of this stems from when she went away to college and had to come home as she couldn't cope with being to far away from home, now I'm thinking something went on there that she hasn't shared with us. Our family has always been particularly close I have 2 other sisters besides her and the 4 of us have always shared things. It hurt me very much that she hadn't shared this information with me. She has put it down to the fact that because I live so far away (I emigrated from the United Kingdom to the USA) she didn't want to worry me. She also said that's one of the reasons she has gotten so depressed is that she couldn't cope with me being so far away.

Anyway my parents took her to the doctor and he put her through some tests and said she was suffering from depression the doctor prescribed Anti depressants (the doctor apparently said it was her choice to take them as they don't like giving them to people her age) not sure how true this is? So now she's not taking the medication because of what the doctor said plus the fact that she can't drink on the medication which seems to bother her. She's on a waiting list to see a counselor, I've tried to talk to her to ask her to talk to a telephone hotline but she's not interested. And frankly my family aren't that worried about it they have said they have talked to her so many times but she puts a wall up and tells you to back off. Apparently my mum thinks that when she gets a job and gets out of the house she'll be able to focus again. But I just don't know, should she be taking the medication? How can I get her talking to someone about what's going on with her?

I'm so worried she'll harm herself, she's made a joke about this when I talked to her on the phone.
Anyone with any thoughts please let me know, it's so hard being this far away not knowing what to do.
Natalie.

Thank you Sunnivara for your advice I spoke with my mother this morning and apparently they are looking into natural supplements I will give her the list.