Re:Concered about my hear rate
At 18 your heart rate will be naturally faster than it will in a few years, so I probably wouldn't worry too much, but sometimes its better safe than sorry.
I wouldn't worry too much if you are doing relatively high-intensity work, but if you're just doing gentle cardio then get yourself to a doctor as 192 is pretty high. I generally max out at about 195 with HIIT, but everyone is different and I'm a few years older than you.
Also, check your resting heart rate. Take your pulse for the next 30 seconds and times it by two to get an accurate result. If your resting pulse is above 90 then its 'probably' just due to your age/fitness.