I agree with Mandy. The packaging for Ainterol pm is discreet.
As for how much growth you'll achieve or what dosage you should take really depends on your body. You're at a young age, which should be a benefit, but who knows how your genetics may influence the development of breast tissue? Others can give you guidelines and share their experiences, but ultimately it's going to take some self-experimentation on your part to find out what herb(s) and doses work best for you. For example, I take high doses of pm for the brain rewiring effect. This works for me and it doesn't hinder my breast growth or incur unpleasant side-effects. For someone else though, this regime may stall their breast growth and/or incur horrendous side-effects or estrogen dominance.
What works for me may not work for anyone else. It takes trial and error I think to customize an NBE regime best suited for you. While this may seem like an inconvenience at first, I'm sure you'll come to appreciate finding an NBE regime that works for you, both in achieving breast growth and having no significant side-effects.
I think Mandy has given some good advice with using pm or any other herb. Start at a low dose and gradually increase to see how your body reacts and how high of a dose you need to start seeing results. You may need a small amount of pm to get breast growth, or you may need a lot. My rule of thumb with pm is start at a low dose, say 500 or 1,000 mg, then increase by 500 mg every week. Depending on how things turn out, I think a reasonable dose to aim for is in the ballpark of 2,000 to 3,000 mg.
As much as you want to figure out everything now, I think you'll have to spend some time taking one or more NBE herbs to see what happens. As far as I know, nobody perfected their NBE regime on day 1. It's an ongoing learning experience. If you notice some changes or feel some sensations in your breasts, that's great!

It means your regime is working. If not, you may have to wait a while longer or maybe fine-tune your regime.
Without any firsthand experience, it's all guesswork as to what kind of regime you should pursue. On the other hand, let's say you take 2,000 mg of pm every day for three consecutive months. You don't notice any changes. While you may be frustrated about your lack of progress, at least you now have some data about what is not working for you. This data gives me and others on this board a frame of reference to work with in regards to giving you advice on improving your regime.