A 3.5 mm VSD is in the small range. If the echo showed a 64 mmHg pressure drop that is very good. It tells you that the right heart pressure is normal (very important). Such VSDs do not get bigger. They stay the same or get smaller with time. Even if the left heart chambers are a tad large currently there is no cause for alarm. This is all likely to improve with time, and I strongly doubt any surgery would be needed. As long as your baby is well, just follow the doctor's plan and it sounds like all will be well.
Just to add some extra details, I have had a report through and it states there is 'pure left to right shunt and a pressure drop of 64mmHg.... There was some mild left heart volume load.... The vsd has only mild haemodynamic bearing'. Please could you explain also what these things mean? Thank you
Thank you very much for your reply, that makes me feel a bit better about it all.