Hi Mally!
Sometimes people don't know what to say to folks when they've been told about an illness. That can go with any illness whether mental or physical. They may be afraid to ask questions because they don't want to hurt you or trigger you. They may not have any understanding of the illness. And sometimes, they may think that if you are depressed, you will make them depressed. Of course, this is not always the case.
I can understand your family wanting you to have more than one friend. It's in having many different kinds of friends that teach us about human nature, likes and dislikes and how to get along with one another. At the same time, having one good friend in your life is a blessing and should be cherished
It sounds as if you are fairly young and have a lot to discover in life still. Things will ebb and flow for you (as they do everybody). I think you and many others would be surprised to know how many suffer from depression at times in their lives. It certainly isn't the end of the world

Nor is it necessarily your fault that friends come and go out of your life. That is the cycle of life
I wish you well!
Hugsss
J