sujal! don't worry i dont think your visa will be denied. just be real and tell the truth to the nvc. if you were studying during the time. disclose that also with your earnings so they can believe on the fact that you were studying so yo had low earnings. with that they make sure that you will make more money once you start regular job which would be good enought for your wife and your son. don't worry about the one year tax. loo for the past 5 years tax also. by the way i am also waiting for letter from nvc.  good luck