I remember this movie that I have watched two or three times. Here is what I remember:

It starts with a girl flying a remote control UFO, she wants to perfect one of her tricks.

She goes to this research lab where I think an elderly friend of hers works.

Later, she believes that she is a martian/alien.

She shaves her hair, saying that hair gives martians rashes or something.

She runs away, and she has a power called the silent scream where she looks as if she is screaming. She shatters windows like this.

In the end she steals/borrows a weather balloon(?) and flies away.

That is all that I remember. Thanks in advance!