Dear Matt,
Part of our anxiety disoreder is we can't believe there is nothing wrong with us. It is so important for us to challenge our thought process.
I too have problems with my heart. I get heart palpitations along with a racing heart. I have gone for blood work and an ecg with good results but when I get a palpitation I am so certain there is still something wrong. I would recommend that you follow the program offered on this site. It will help you to cope during these difficult times.
I get the sense you are afraid because you have a small child and think to yourself what would happen if you're not around. We all on this site face similiar fears. Read through some of the message boards and you will find you are not alone.
I have cut out chocolte from my diet, limited myself to two cups of coffee a day, and am cutting down on the amount of sugar I use to eliminate some of the stimulants in my life. I have found that my heart palpitations are decreasing due to these changes. I don't know if any of this helps but I just wanted to let you know I can relate to what you are going through.