Unless they are plastic breasts aren't going to be perfect.
Some women have breasts that differ in size, one is larger then the other, no big deal it's just harder to find a bra that fits you.
As for shape, I can't say that I totally understand what you mean, but if they have always been different shapes then its possible that, that's just the way they are.
But if they have changed recently/rather-quickly then you may want to go get them checked out.
Depending on your age the above fact may not matter, if you are in your earlier teens/pre-teen then it's perfectly normal for your breasts to change shape and size since they are still growing.