She’s single and flirts with you and “Not to mention she’s told me she’s wanted to sleep with me a while back”, so why are you expecting to you’d be “making her very uncomfortable”? And why when she asked before, didn’t you say yes?
Assuming you’re just confused, two ideas: 1) Flirt more seriously, leading to touching, stop when/if she responds unfavorably. 2) Ask her if she still wants to sleep with you.