Hello Shy.
Welcome to the forum.
I think CK offers some good advice on what kind of regime you could start out with.
Before starting out though, I think it's important to first decide if you really want to go through with this. You mentioned you've been contemplating this idea for several years but have been afraid to put it into motion. What is it that you're afraid of?
There are some other crucial matters to consider. First, are you single or do you have a significant other? Second, do you want to have your own kids someday? Third, how would you describe your gender identity? Fourth, how do you think you feel when others start to notice and comment your breast development?
I don't know your sexuality, but a lot of members who have girlfriends or wives have reported a very mixed reaction from their significant other in regards to NBE. Some women are adamantly opposed, some are supportive and some become more tolerant about their partners pursuing NBE once they see the improvement in their partner's mood and behavior.
NBE can alter you body a lot more than simply growing breasts. Pursuing NBE may make you infertile and/or hamper your ability to attain and maintain erections. Unless you're certain you don't ever want to have kids, I suggest putting NBE on hold for at least the time being. Also, I suggest you think about whether a loss of male functionality would be a problem with your current or future relationships.
You said you want to transform your body into your ideal female form. Do you plan on eventually transition to living female full-time? Or is growing breasts as far as you want to go?
When you say you feel shy about pursuing NBE, I presume this means you would be uncomfortable about others noticing your breast development. Let's say you do pursue NBE for a while and you achieve some decent development. Imagine how you would feel when you go to the doctor for an exam or something and he/she asks you to lift up your shirt. Would you hesitate? Would you feel ashamed? What would you say when your doctor asks questions about your breasts and whether you would want to pursue treatment to reduce or eliminate them? Would you have the confidence to say you're not bothered with having breasts?
On a final note, unless you have a lot of busty female relatives or just happen to hit the NBE lottery, you're probably not going to get D-cup breasts. A lot of genetic females never attain D-cup breasts, and their bodies are geared towards achieving breast development in their teen years! I suggest looking through the bio-male picture threads to get an idea of what kind of development you can expect to achieve.
own. 
