My son had a large VSD fixed at 6 weeks just over a year ago. He was tube-fed from birth as he had some other, unrelated, issues and had a very low birth weight. He was also on fluid restriction.
He recovered pretty quickly from the surgery. He came home a week after operation day. He was able to drink enough from the bottle shortly after he came home and the tube came out 2 weeks after he was discharged.
As for hitting milestones, do expect a delay. As my son was tube fed from the start, and had to learn to drink properly at 2 months old, and we had a pre-speech therapist help us with this. In terms of eating he's about 2-2 1/2 months behind, although we started weaning around 6 months, he wasn't ready for.
His gross motorskills are about 3 months behind, as they reckon his body was in survival mode the first few months. He didn't start crawling until 13 months old and we have a physio right now to help him as mentally he's where he should be and this leads to much frustration on his side.
I felt his recovery was pretty quick, he was a different baby, straight after the op. His heart rate had dropped, his blood sats were fine, his respiratory rate was much better. He started looking much healthier and getting a normal colour after a few days, it was a massive change.
As for tube feeding, for us it was amazing. My son couldn't drink more than 10mls, maybe 20 in one go. He was also on a fluid restriction and on diuretics until he was 3 months old. If you breastfeed, they can give expressed milk through the tube. I was never able to breastfeed due to the fluid restriction, but I expressed for about 2 months until it became too much to cope with. We also had special formula for a while and they had put additives in the breastmilk to help him grow.
Dealing with the tube feeding at home can be a bit tricky, but we were shown exactly how it all works and it was fine in the end.
Fixing a VSD is a straightforward operation, but nonetheless it really hits you hard. My son is almost 15 months now, happy and healthy. The only reminder of the whole ordeal is the massive scar on his chest, but it's really faint now.
Good luck for the coming period. Nothing prepares you for this. Feel to to send me a message if you want to chat.