Unfit with slow heart rate

I'm 28, male, and for the past several years I suffered from tachycardia, with my average resting heart rate around 125.  Over the past 4-5 months however, I have lost around 40 pounds, and during that time, my heart rate has slowed down to an average of 55-60, sometimes dropping as low as 45 or so when I'm sitting and very relaxed.

I am in terrible shape (still about 60 pounds overweight) and can barely walk for 20 minutes without feeling sick and lightheaded, and my heart rate during exercise can jump as high as 160 just from walking up a slight hill (I wear a wristwatch monitor while I'm exercising).  This really makes me question if my heart should ever be dropping that low, as everything I've read has always said that heart rates that low are only normal in athletes, which I am anything but.

The thing is, less than a year ago, I had a 24 hour holter which was normal, multiple EKG's, and an echo which all came back completely normal.  I have no health insurance like a lot of Americans these days, so I can't just go back and get more expensive tests done.  I'm not really sure what to do, but I am definitely stressed out over the whole thing.  Any suggestions?

[Cleveland Clinic]

It is very difficult to say what your heart should be. As long as you feel well ,that is not lightheaded or dizzy when your heart rate is in the 40s then it is acceptable. I would advise you to continue your efforts at weight loss, through diet and aerobic exercise. As this occurs then you can gain in fitness, and improve your exercise capacity.