Was told I have an incomplete left bundle branch block.?

I had an EKG preformed in nov 09 and I fell an broke my ankle and it was completely normal. Then about 2 weeks ago I was feeling short of breath so we to a local clinic where there performed another EKG and this time it showed an incomplete left bundle branch block. So then the practioner sent me to the hospital where another EKG was preformed and it also showed the lbbb. The dr acted very nonchalant and told me not to worry about it but I'm really worried about it. I'm only 22 and have a toddler and I don't want her to grow up without her mom. The tests the done that night was an EKG, blood work(CBC,cmp,cardiac enzymes) a chest xray and a chest ct. All the tests were normal except the EKG which also showed sinus tachycardia(prob cause I was so scared). So my question is should I take this Dr's advice and not worry or should I are a cardiologist? My 2nd question is if I had an underlying cardiac condition like heart disease would these tests have showed that?