I'm 13, pls don't hurt me...

So, I'm in 8th grade and after I left my school for another, more educated one, my old friends just abandoned me. When I came back for the 2nd semester, they kind of acted like I was just some stranger. There was a "group" party the other day and they didn't even tell me. When I asked the only one in the group that would talk to me, they said they has no clue as to why this was happening. I don't know if I have any disorders of any kind, but I'm pretty sure I have depression and/or anxiety. My sister acts like she is entitled to only have a disorder in the family, so apparently, I don't have a disorder and I'm just making things up. I need advise as to if I should ask my dad or mom for a checkup. (ps, I realized that I was a shitty friend to the group, but there's such thing called, "forgiveness")