I keep thinking about the past?

I'm 15 y/o girl. I don't know why I tend to think alot about the past, happy or sad. Just 2 months ago I was the pitcher of my softball team. I played well in the first game and was very happy about it. Then on the third and second game, I did quite a lot of mistakes. I have this guilt in me, I felt as if I was responsible for the loss of my team. Reminisce a lot about the happy times of training and I remember the times I had with my Captain. I just look up to her a lot and feel sad for letting her down. She told me when she picked me as the pitcher , "Hey, you are the pitcher now. Don't let me down." I remembered the part she screamed " ARE YOU AWAKE NOW?!?!" to all of us. I cried secretly. We came in second... It's just still disappointing to me, while my other team mates are OVER the whole thing.