My attachment to people is destroying my mental health; it feels like grief

I am 21F, I suffer from severe attachment issues, and when I say severe, I truly mean it.

​When I get attached to people, they affect my mental state terribly, and it can last for months. My mood for the day depends entirely on them; they can make me incredibly happy, or they can make me so deeply sad that I can't even eat.

​The problem is, I can't really call this love. It feels selfish, because I don't actually care about their well-being. What matters to me is that they are in the exact position and place that makes me happy.

​I think I’ve been dealing with this since I was 14, and I just can't seem to stop it. I am truly suffering, crying, and hurting so much, it feels as intense as mourning the death of a loved one.