Certain birth control pill which contain combination of both estrogen
, more likely cause increased breast size in women with some other side effects. Though, increased breast size is not a permanent side effect of it and in most of the cases, breast size returns to normal after stop taking the pill or switch to a low dosage birth control pill (contains only progesterone).
In general, full fertility
comes back within 1-3 months after discontinuing the birth control pill and it totally depends on commencement of normal regular period.
Hope, this information is very much sufficient to clear your doubt & confusion.
Be well & take care.