Hey Brigitte those meets can be very hard. Its a good practice as an athlete to stay within yourself and keep calm save your energy for the races. Focus on the things you can control.
Also for your races do you have a race plan the breaks down what you would like to accomplish over the course of the race. In track there are usually two types plans placing plans and time plans. Placing more focuses on racing the competition and forgetting about time. This might be good for you to try some time even if your the best girls in the field. Go out at the pace of the group and at some point in the race make a hard move. Time plans are usually based on pace and I think for you when you run the mile a good plan would be try to run 85sec pace for the 800m then race like the third lap is your last lap and hang on at the end. It seems like you need to work on breaking out of the rhythm you get in.