I need help with my relationship?

my girlfriends parents won't let us go on date or hang out except during soccer. But her mom let her sleep over at her old boyfriends house ( her mom was there ) WTF?! and she lets her go to another guys house. how can i get her parents to trust me enough to atleastly hang out with their daughter whom i love ill see her tomorrow at our soccer game and thats it until next week until we practice. do i get to see her? yes but were practicing then we leave and we play a game then we leave i talk to her everynight on the phone. my mom wants to start having pool parties after games and what not so i can get the chance to see her but what if her parents dont let her? I am really hurt her parents let her go and sleep all night at another boys house but wont even let us hang out at her house to where her parents can watch us. and she went on a date with her last boyfriend ( but it was a sport thingy since his sister played on her travel ball team ) but it was still a date i guess. and he turned out to be a complete hole but i would never hurt her in amillion years. I want to prove to her parents that i am trust worthy and i want to see their daughter in there house to where i they can watch me. i am in 9th she is in 8th.