Hi Luk. Sorry for taking so long to answer. I have not had any experience with what you have posted about. I am several months behind you. I will say that yes. It sounds like you are having development. During the development of breasts there are grapelike nodes in the tissue called < i think> aveoli that develop. Also there are many ducts and and other stuctures to be developed. The below link shows the anatomy of the female breast
http://www.breastnexus.com/showthread.php?tid=5176&pid=10006#pid10006
I have read a thread or two from the old site. In these threads the authors mentions that they went off of glandular theropy to herbs. Their breasts became much more tender and hurt more. What you may be feeling is the result of changing programs.
A site that goes over the development stages.
http://www.007b.com/breast_development.php
It is understandable that you may be concerned and rightly so. I would consider what doctor you trust the most and go in for a checkup. That way you can avoid worrying over nothing. You will need to go in to see a medical professional sooner or later to have a mamogram done. Just like the GGirls, if you develop breasts, you need to have them examined from time to time.

I would also recommend looking over the internet for articles on breast care. Knowing ahead of time what kinds of problems you may have with your breasts. Can save you some time, energy, and worry.
I hope some of this helps. I think what you are expieriencing may be a normal developmental stage. But I can't say for sure. Perhaps some of the ladies who visit this site. And have gone through the development process can chime in on this question.
Good luck. Keep us up to date on your progress.
If I come across anything else I'll let you know.
Best wishess and good journey
andy