Confused. Please help

I me this girl a few months ago at my new job. I instantly fell for her an she seemed interested in me as
Well. Time has passed by and we've messages went out once and everything was well. We would flirt and
Things like that. Our Christmas party was 2 weeks ago and we sat right in front of each other. She started
Rubbing her leg against mine so I started to feel her leg. She texted me that night that I was driving her
Crazy so I told her we have this tension between us that we should get rid off. She agreed and the. I said
But you're always busy and I said this because I've asked her out 3 other times and she said she was busy. Anyway she texted me Friday afternoon to do something with her and I said yes. I was extremely happy
And anxious. We went out then we went to a parking lot where I started teaching her how to drive a manual car. So stayed there for a couple hours talking, making out and a little bit more where I won't go into detail. So the next day we don't talk at all and today I see her but she was acting a little bit weird. I was thinking because at work were always busy and no time to talk. I hate this and I feel like shit when this happens. So the thing I want to know is why does she text me sometimes and other times her text are a little bit cold and other times we go days without talking. This kills me because from what happened 2 nights ago I have more feelings for her. Why does she act so distictent at work. Why don't we text everyday? This is killing me. I wish I could talk to be everyday.. Women, have you ever done this to a guy before. And why do you do it?