So there's a girl who I've been sorta kinda with for a few weeks, we banged and cuddled and watched awful TV. I want things to go farther

So there's a girl who I've been sorta kinda with for a few weeks, we banged and cuddled and watched awful TV. I want things to go farther than they have because I really care about her and I'd like to spend more time with her, but I'm not really sure she's in for the whole relationship bit and not just sex. I know I should probably really talk to her about it, but I'm not sure if that'll ruin the whole casual sex thing we've been doing that I really like. What should I do, friends?