The surface on which you run may make a difference, as do the starting blocks and the turns. Also the wind (if outdoors). And the tracks at your high school may have been under regulation length.
Maybe now, since you age every day!, you need foods and drinks to help contribute to your running. Maybe a vitamin in the morning, and a replenishing drink and meal to help boost your speed! Practice and eat healthier
I'm currently a freshman at a university with a scholarship. My senior year in high school I was running 48.8 in the 400 and 22.00 in the 200m and this year in indoor track ive been running 22.6 and 49.8 but now outdoor track I've been running 50.6 and low 51s and 23.5s in the 200. I'm so dissapointed of these times and don't know exactly what is going on? If someone can please answer this for me it will be greatly appreciated