Slow heart rate, chest pains, frequent yawning/hard to breath

I don't know.  My family has a history with these things, apparently there's something that runs in my family to where a vein...or some...blood vessel runs through the heart when it should go around- causing the heart to pinch it...which can cause chest pains and palpitations. It's said to be benign, and when I brought up that I was getting chest pains, palpitations, and was getting pretty scared- my family pretty much assured me it was all okay.
I've tried to exercise, get my heart stronger...but it never seems to do much.  I can be okay one week and the next I can go back to square one it almost feels like.  I mean, I skip weeks of working out just cause I feel like I'm not strong enough to do so.  I have never fainted, or really felt coming close to.  I've been lightheaded, but no...not really the feeling of about to pass out (which I know the feeling).  It still scares me from time to time, these chest pains and palpitations, but I try to tell myself it's okay, and the  fear is just in my head.  I'm not gonna lie, I do have the tendency to assume the worst - I have the tendency to jump to conclusions about my health, and hopefully all of them aren't true..  Back to the main question, I fear it's something more than my family's history of benign heart problems.  My heart rate has been weirdly slow lately.  I'd saw around 60 beats per minute when I count, which seems okay, but it's unstable...sometimes it beats faster, sometimes it beats slower.  The worst part is that it just FEELs like it's beating too slow.  I've been trying to take as big as breaths as possible, I have trouble laughing too much cause I feel...light headed or something, have chest pains, and feel over all extremely uncomfortable and tired.  I've felt like this before, and I've gotten over it okay, it's just the more I look into it the more it scares me.  It's been for two days, and I hope tomorrow (by the third) I'll be better.  I also feel like I have sleep apnea, because I do sometimes find myself waking up and feeling as if I....forgot to breath.  I wonder if these have a connection, or if they're separated.
I wish I could tell you the actual name of the disease that is common amongst my family, but I can't remember.  My uncle's a doctor, and he's the one who told me not to worry.  I trust him, but here's my question - does it seem like that?  Is it possible to get these side effects and still be benign?  Should I push myself to try to exercise more and just...maybe build up my heart a bit better?  Any help is appreciated.  Oh, and I'm an 18 year old female.