There really is only one way to gain real natural breast growth. Hormones. I'd be curious as to why you want to go down this route. I note from your profile you're married. If still together, what does your wife think of this? Having breasts is an interesting thing. For a start, even an A cup is very noticeable on a hot summers day when you're only wearing a t-shirt but are wandering the streets a la male. You get stared at. It's great to have this as a fantasy [I'm not saying you do!] but the downside is that, unless you're going down the M2F route, you have to be prepared to take the flack of being an obvious guy with breasts when in male mode. Trust me, you can't hide them. And after 18 months on hormones my breasts are obvious under a winter's jumper.
I will admit my opening line was a slight fib. I started to develop natural breast growth long before I decided hormones were the way forward ...