You Need to supply more information, height, weight, smoker, drinker, what method did you use to take your HR, was it a rest, are you normally fit, diet etc
You will need to do an ECG to get a class 1, so you may as well do it now and it would tell you a definite (well, 95%) answer .
100 at rest for a tall fit adult aged 17 would be a little on the high side, 100 for a slightly built small unfit adult could be quite normal, but , as the DAME's are always saying , everyones different!.