There is nothing wrong with it, and not something to be ashamed of. It's perfectly normal and healthy.
Is it normal for a girl to masturbate?
'Norma'l is relative, depends with what tickles your fancy. .
It is normal for a girl to enjoy touching her body if she is old enough to do that. There is nothing wrong with it and it is a good way to get to know your body and learn what feels good to you. We are all different and enjoy different things.
I really don't think it matters how often you do it, as long as it continues to be a pleasurable experience. You could make it part of a pamper night - have a nice bath, apply some soothing lotion and then enjoy exploring your body.
It is however, something that the older generation tend to have a problem with, some feel that no one should do it. However, in reality most people do, or have done this.
If it feels good, what is the problem? No one needs to know unless you choose to tell them ;-)