Rob already has you covered, but, I'll offer some snippets of wisdom.
Like yourself, women open up relatively early (and without my pushing for it) in conversation and it boils down to your vibe. I'd guess and say that you are pretty chill, and your body language suggests that you're mellow but also willing to listen. In my case, my body language and walk suggest that I don't waste time but I'm still pretty care-free and women open up fast.
Everybody has this ability to read others but women maintain more of that ability as they age than men do. You'll see this same trend with abnormal psych patients, and mental disorder patients - they know who will listen to them, who will not judge them, and who they can just talk to. Kudos to you for having that vibe because it's a giant piece of the seduction equation/puzzle.
Having the vibe that allows women to open up to you means that they are comfortable with you and when women are comfortable with you then they are willing to let you into their world and inject whatever qualities you have into it; namely sex and adventure. If she's opening up - keep your natural vibe going and start to introduce sexual content. If she runs with it then take her home