Dear New Mom,
Obviously, without seeing your child and doing an evaluation, I can't say what the best thing is for him or her. The signs for which we look for evidence of congestive heart failure include getting out of breath and/or getting sweaty with feeds. If your child is not doing these and is having at least reasonable growth over time, it is likely that the VSD is what we call, "hemodynamically insignicant", which means that it does not need to have surgical intervention. Even if the defect is open but small, there is no evidence that (other than a very slightly increased risk of infection of the heart) there is any adverse impact on the lives of these kids. So, we have plenty of adult patients with small VSDs who have never had them intervened upon.
The fact that they took your child off the Lasix and Digoxin is a very good sign, especially if he is gaining weight, albeit slowly, without it. And without signs of heart failure like sweating or tachypnea, those are also good signs that he's fine to wait. While a VSD repair is probably one of the easiest OHS repairs, there are still very real risks, and if your son is in a stable state, then he is far better off postponing surgery.
Our DD was born with a moderate/large VSD and ASD, only she was in heart failure by 10 days old, was placed on Lasix, Digoxin and Spironolactone and NG tube by 6 weeks. She was in very significant heart failure. She is now 3.5 years old, and surgery free. Both defects improved enough that surgery ended up not being warranted. She is still small, at 3 years, 7 months she is still only 28.5 lbs, but she is perfectly healthy!