The reason for your breast tenderness and increased size, could be a possible pregnancy or effect of hormones from the birth control pills.
The estrogen and progesterone in birth control pills can lead to breast tissue growth and fluid retention, resulting in bigger breast size and sore breasts.
You should do a pregnancy test, since, as early as the first few weeks after conception, breasts seem swollen or enlarged, and, very tender with tingling nipples.
If you are very young and during puberty, the rapid breasts growth to an excessive weight in a short period could be a condition known as juvenile breast hypertrophy.

Best wishes!
Marija