Everyone's different, in the cardiovascular field just as in say, facial features. So there's a big 'spread' of pulse rates and yours just happens to be on the higher side of average. A similar question being asked here (now) on Answers is at the opposite end, -about 50 bpm. So if it hasn't suddently changed, there's nothing wrong with your pulse rate range.
Provided it rises properly with activity (stress
, physical exercise, etc) and falls back to the original figure when resting, then it's delivering the right cardiac output. It should return to resting rate within a few minutes. Your pulse rate, multiplied by the volume of blood ejected from the heart at each beat, is the cardiac output, (which is dertermined by your brain) so if your normal pulse rate is on the high side, then it simply means your left ventricle is probably smaller than average, -but the output is the same as anybody else's. (Note I say 'average' -not 'normal'...- you're not abnormal, even though your pulse isn't average,...your cardiac output will be normal, and that's what matters.)
is probably unconnected with your pulse rate question. It's quite common for young people -especially females of your age-, to suffer from this temporarily but it usually works its way out of your system by the time you're fully mature physically. If you want the posh medical name for it, it's called 'syncope', and you can read it up on Google, or the reference below.
3 things happen when you exercise. (1) the blood vessels dilate. (2) the pulse quickens, and (3) the heart pumps out a greater volume at each stroke
. But the mechanisms that make these happen are all different, so they don't happen synchronously. Eventually, they all stabilize at some output level, but until they do, you'll feel the exact effects you describe, -'trying to catch up' and 'fluttering', etc. All predictable, and quite normal auto-reactions, -honestly!. - If you didn't feel and experience these effects then you'd not be normal.
Chill out, stop worrying, and enjoy the best years of your life!