You said you’re a direct person, so be direct. If you like her, tell her plainly and without beating around the bush what you really want. If you want the relationship to become official instead of just flirting and talking, then say so. If you’re looking for something more serious, make that clear.
If she agrees, then great—you’ll know where you stand. If she doesn’t, then it’s time to move on. That’s really all there is to it.
It should be easier for you since you already said you’re the kind of person who prefers being straightforward and honest about what you want.