My outfit doesnt have pockets and i need to bring my phone and keys and wallet so is it okay to bring my backpack to the movies? (Its the classic jansport backpack btw)

Yes ofcourse it's allowed, you can even put candy and drinks in there to save you paying big $$$ on their candy!!!

I do it all the time, you'll be fine :)

bring a purse

yes you will be fine, but understand that you mite be subject to a search...