I, too, am very sorry you are going through this with parents who aren't supportive. I want you to know that you are not alone and that you will get through this. In fact, we have a sub-forum here dedicated to gender identity. You might find kindred spirits there who are able to give you the support you need.
I really don't think you would lactate on any herbs. Even if you use a pump and herbs it would be very difficult to get yourself to lactate.
I don't think maca would cause you any negative health issues in appropriate doses. Whenever I am interested in an herb or vitamin/mineral I look it up on WebMD to see what the possible side effects are and proper dosage.
http://www.webmd.com/vitamins-supplements/ingredientmono-555-MACA.aspx?activeIngredientId=555&activeIngredientName=MACA
Can you find a doctor in your area who specializes in intersex and can educate your parents on what that means? So many people are clueless about it and education can make a difference. I also hope you have/find a doctor that you feel comfortable with and can let them know that you don't want T and would prefer to be neutral/natural or try female hormones. I'm curious, do you know which intersex condition you have? Did you have a hormone panel done?
Because of your age we all feel very concerned about giving you advice on herbs, etc. Herbs can do harm if not taken appropriately.
That said I have a couple suggestions for you to consider.
Massaging your chest can help stimulate breast development. Here is a thread with links to massage instructions:
http://www.breastnexus.com/showthread.php?tid=19838
Here is a thread that Lotus put together for bio-males growing breasts. It has a lot of information about hormones and what they do.
http://www.breastnexus.com/showthread.php?tid=17658&highlight=spearmint+tea
Here is a link to the Gender Identity sub-forum. You might enjoy reading the stories and experiences there.
http://www.breastnexus.com/forumdisplay.php?fid=53
As a growing teen it is important for you to be physically active, eat healthy and get plenty of sleep.