She was down to chill meaning you should have said sth in the lines of "Oh, OK then, you might wanna come and check out my place, let's chill there" and if the interest was as high as it seemed to you or as high as you're describing, your confidence to invite her back to your place alone would have got you the lay.
Stop offering dates to girls you cold approach. I haven't dated anyone in 5+ years. Dates are special, for girls that deserve them, that have proven themselves. This is not the 50s anymore where you take a virgin on a date and propose to her cause you want a wife for the home and for kids. Bitches be banging several guys and they want you to take them on a date? ****s no