Bra Sizing Problem...(13 year old)?

I recently ordered a bra from Victoria's Secret (not padded) in size 30D. Since I've put on quite a bit of weight since last year (more than 20 lbs), the bra fits a bit snug. The cups sort of fit better than my other bras and I have no problem with them staying in place. The center of the bra also sits flat on my chest. The band definitely fits better than a 32, but it's hard to clasp... However, I can still stretch it about 1 inch, and the straps are just perfect. There's only one problem with this all, really. It's not really noticeable with a shirt on or even with a shirt off, but if I look closely, it appears that the cups are maybe a bit too small? Not by much, but my boobs bulge out a bit at the top---and from the side it's more noticeable,---giving the quad-boob effect, haha. Could this be because the band is too tight or is this only attributed to the cup size? If I lose weight---which I'm planning to do---and the band isn't as tight on me afterwards, will this fit?