Laidbackruby
I too worried about this, but softer breast that don't leak are NORMAL. Basically your breasts beome more and more efficient at producing milk and containing milk and that's why they feel that way.
Very important: You have NOT been starving him. As long as you are offering milk when he asks for it and letting him feed for as long as he wants, then there WILL be enough milkfor himm. If he needs more, he will feed more regularly and build up your supply and then the feeding will calm down again.
The risk you take by introducing formula is that it can artifically stretch a baby's tummy a the same time as breaking the sensitive supply/demand system and reducing your milk supply. This means babies can feel 'less satisfied' by breastfeeds and mums can have less milk to offer. Thjere's also the emotional aspect of not feeling you you have enough milk for your baby. It can effect breastfeeding in a negative way and as you have done so wonderfully well to establish breastfeeding and your baby is doing so, so well too, I really would talk to a breastfeeding professional to get some reassurance before you decide wether or not to keep giving formula to your baby.
My DS was very colciky and cried allot, his weught gain was always very good and above average. It is a typical response to say a baby his hungry - but there are so many other reasons and the fact that she is putting on weight means you have been doing just fine with breastmilk.
Breastmilk is a totally different substance to formula. There are now instructions, no way to see how much milk your baby gets.is no set amounts that a baby has to have at set times. The baby takes what they need. How it feels and how you baby is and trusting that it works is they key IMO. My formula feeding friend would have huge volumes of formula compared to my breastmilk and that worried me at the star, but when you accept that the method of breastfeeding and the milk itself is totally different, there is no need to compare or calculate amounts etc.
Sorry for the long post. I would just jhate to see a succesful BFer have their hard work undone because of lack of confidence or bad advice.
Good luck in whatever you decide.