Rayvin,
Sorry to hear that you are having irregular heart beats. I get them too from time to time and they can be quite scary.
Just from your post it sounds to me like your problem could be anxiety related. I would call your doctor back and tell him/her that you notice your heart beat feeling "off" when you are nervous. He may prescribe medicine or at least tell you what you can do keep your heart rate calm and regular. I know magnesium can help with heart arrhythmias so I consider taking it as a supplement, but talk to your doctor first.
I'm not expert, but just from my personal experience the following things have helped me:
1. Drink plenty of water and drink it in place of too many sugary and caffeinated beverages.
2. Eat healthy--whole grain breads and pasta, brown rice, fresh fruits and veggies, lean meats, low-fat dairy products, and sweets sparingly. (I can't live without a little bit of chocolate each day

).
3. Exercise regularly. A daily 30 minute walk or maybe moderate to intense cardio exercise 3-4 times a week. But always check with your doctor first to see what is the appropriate amount of exercise for you.
Good luck!