What's wrong with my new glasses?

My new glasses are meant for distance, but... they absolutely suck.

Everything looks blurry and horrible, and like I'm in a funhouse. Everything is magnetised out of proportion, and things look way larger out of one eye than the other. Even colours aren't appearing properly. These are honestly the worst things I've ever used. They're supposed to make my distance vision better? I can't see 2 feet in front of me, let alone 10. They slide off my nose every five minutes as well, as if being half-blinded wasn't bad enough.

I can see about a thousand times better without them on (mostly because I'm not so distracted by the shrooms-esque vision), but my mum says I have to wear them all during school.

What's wrong with these crappy, crappy glasses?