Oh yeah, I get that a lot. Especially after i've used my asthma inhaler, of have yet to take my dose of clonazepam. That heart rate is within the realm of safety, and probably even a physical manifestation of your anxiety. Then the anxiety causes you to worry about your heart rate, so its a vicious cycle.
As far as your heart is concerned what you should really be watching for is your Blood Pressure. Use one of those machines at the pharmacy that take your blood pressure whenever your there and keep a record of it for your doctor to review. (make sure to sit down for 5 minutes first as to not skew the results). Typically the top number doesn't matter all that much. The bottom number, Diostolic or whatever it's called is what you want to watch for. If it's consistently over 90 then it's something to talk to your doctor about for sure, but even then you're young. And a person as young as you look having a heart attack is totally unheard of in the medical community. :)
In other words, don't worry, I think you're going to be just fine for now.