Bad friend?

So I’ve been wondering if one of my friends is truly a good friend or if it might just be in my head. One of the red flags is she talks to me about people she knows. Wether it be her family, friends or coworkers. She will tell me great things about them and why they’re great people. But if something goes wrong or she’s in a mood, she will make negative comments about them and sometimes personal secrets come out. While in most trusted relationships it’s common to talk shit but typically this is about people you straight up don’t like. So now I wonder if these peoples are supposed to be her friends, is the same thing being done to me? Talking about me to other people in a negative way. Another red flag is when I’m feeling down or just need to vent, I sometimes get interrupted by her and somehow the convo flips to where it’s now about her. Overall we get along great but these things just make me question if she is a good friend