My 8 year olds ( girl) breast is bigger and swollen than the other is this normal ?

Depends: Not all breasts have to be of equal size. However, if one of her breasts is swollen and has any pain or redness associated with it then this can be associated with a superficial skin infection. I would have her seen by her doctor if she has any pain, redness, fever or any discharge coming from the breast.

Early development: As a girl enters the early stage of puberty, breast budding is the most noticeable sign.One side may come out before the other and as the breasts develop further, they may maintain some difference in size for months if not a year or more.They may be slightly tender in the beginning but should never be red or drain. If so a visit is needed.