Increased heart rate

I am a 21year old male.  I am now on a beta blocker called propanolol and my resting heart rate as of now is at 72bpm while on the medicine.  Before the medicine my heart rate would usually be resting at around 90bpm but would sometimes be ridiculously high and in the 120's.  I am very active and work out about 4 times a week.  While working out my heart rate is usually in the 180's or 190's if i am working out really hard and running.  After i work out i find that my heart rate stays high for several hours after even while resting.  I also found that my heart speeds up after eating.  Even while i was young my heart rate would always be high while working out.  When i was 15 and in high school we used to have to wear heart monitors and keep our heart rate above 150 in order to get an A for that excercise and i would put fourth little effort and my rate would usually be in the 170's.  I was very active my whole life and played three sports from the time i was age 5 until age 19.  I weigh 165lbs and am 5'11''.  

I recently went to the doctor and got an EKG and my results were "normal." I also got an order to get and ectocardiogram in order to test from micro valve prolapse.  I have yet to get the results back, but i was just curious if anyone could help me out if you have any idea what is wrong with me.  

One last thing, I also feel that once i notice my fast heart rate i start to freak out a little bit which causes me to have severe anxiety, which in return increases my heart rate even more.  I am expecting my first child in June and am under a lot of stress i guess, but i don't feel like I am worried or anything..maybe it is just sub-conscious?  If anyone can help I would greatly appreciate it!