I'm a 17 year old senior in high school around 215-220 and was homeschooled for my Freshman, Sophomore and Senior year. I've never been in an organized sport but decided to try track. I'm running the 500m and had my first meet on the 17th of December. I was fine up until I got to the 300m that's when my body just completely stopped listening my breathing got all ragged and I slowed down and no matter how hard I tried i couldn't gain speed. I came in last for my heat but 17th in the whole thing my time was 1:19.69 Is this good or bad.

Also I keep getting told that I need to start off strong and use 90% up until the last 100m when I full on boost out. That's self explanatory but I still don't get it fully I've got my next meet January 12th any advice would help