It's a condition called Macromastia, also known as hypertrophy of the breast. The short of it is that the breasts keep growing. A lot of people at her size have this condition and continually grow. You can often tell from visible signs such as breast discolouration, large differences in size between the two, and poorly defined areola. You can see it in this photo that her right breast is visibly larger than the left, and that the end of the areola blends into the rest of the breast.
If you're not aware of the tool ripme yet, I can highly recommend getting it. It supports erome.
The download link is a bit below, but here's a link to the latest release.
Download the ripme.jar file and just run that. It's pretty self explanatory from there.
What are you using to add subtitles? If you use Aegisub, you can define different subtitle styles for different people without having to manually color each subtitle. It's a great program.