I'm not sure, because high levels of prolactin are usually correlated with excessive breast growth (prolactin increases with pregnancy which is why some women get bigger breasts during pregnancy) however I'm not sure whether higher levels of prolactin is directly responsible for larger breasts. Also maybe because yours is abnormally high it may be disrupting other hormones in your body, not sure. Or (and please I'm so sorry not to freak you out) IF you have a pituitary gland tumor it's messing with how your body's receptiveness to hormones. This is all speculation of course, so please bring up these concerns with an OBGYN/GP.
Also, not sure why they thought your estrogen levels are normal when it's below the standard range? It shouldn't matter whether you don't know which cycle you're on because it's lower than the minimum ranges for luteal/follicular/ovulation. Also bring that up with OBGYN/GP.