Is there a problem with me? I'm scared.?

I'm 15 years old and I feel really alone and that life is a burden some days. And other days I'm slightly cheerful and I can hold a smile for the day and it actually being real sometimes. When I start feeling alone and suicidal my thoughts go back to my father who commited suicide when I was two years old. Almost everytime I think of him I feel as if I wasn't worth it for him to keep living. Like I wasn't enough to stay. He abused drugs thoroughly and grew up with an abusive father who treated his dogs better than my father. I don't abuse drugs, I understand that they are only a momentary shade pulled over the reality of life. I remember feeling this way before I began menstruating, so I doubt it's PMS. And I feel this way a lot of the time. Right now it's harder and I feel really lost because my best friend just had a child and I feel like I am not needed. Though another part understands that this is the time that she will need me the most. I saw the father of her child kissing and hugging his child when he had to leave, and I just felt like I was really alone and that I couldn't even move to get off the couch. I felt so weighed down and lost that I physically couldn't move. It took all of my effort to raise my head so that the tears wouldn't fall. I just want to know if this is a problem I can fix. Am I clinically depressed? Or is this an abandonment issue. I'm scared, because I honestly don't want to feel this way. But I'd rather embrace it because it would be so much easier to just lay somewhere and feel this numb. I'm scared.