Heart trouble only 21!! Help!!?

I'm 21 years old and I'm 5'7 and about 170 lbs.. About a year ago my father was having some heart issues and they found out he is actually missing a heart valve.. I've never had heart trouble but the doctor did inform my dad that it is hereditary and I need to get checked (I'm his only child) well I have a daughter that's almost 2 now and about 4 months ago I decided I needed to get serious about losing this baby weight I still had!! So I went to a diet doctor where I was prescribed phentermine.. It has done wonders for me., I started the diet 4 months ago weighing 210!! And now I'm down to 170 or so!! Recently though I've noticed my heart rate feels very very slow and almost like it's fluttering.. So I went to my family dr and explained to him what I felt like and that I'm on the phentermine.. He said phentermine if anything would speed your heart rate up, so he did an EKG in his office my bpm was 37!!!! He said it also was showing palpitations so he thought maybe it was the phentermine so he took me off of it for a while.. But about a week later i started back taking it because I really didn't feel any difference but they gradually went away and would come and go randomly.. Well now my heart is doing it again.. I just checked my heart rate and it was about 47 bpm.. Could this be a sign I too am missing a heart valve? I don't know what else to do.. PLEASE HELP!!!!!!!!!!