A little back story first: I met this girl, (a friend of a friend) on a night out about 10 months ago. She wasn't really my type so I didn't make any moves but I added her on Facebook and we commented on each other's statuses from time to time but nothing flirty. A couple of weeks before Christmas, completely out of the blue she sent me a message on Facebook inviting me (as her plus one) to a party our mutual friend was throwing. I had nothing better on and thought there could be some tail at the party so agreed to meet her there.

The party was a small affair and pretty lame - no girls except the ones I already knew and had no interest in. The girl who invited me however was all over me like a rash; kissing me and plying me with alcoholic drinks of her own concoction. I was the only one she talked to and we spent most of the night separated from the rest of the party. Although I hadn't previously thought of her in a sexual way, I found myself attracted to her.

In the small hours of the morning she retired to the spare room for the night and I stayed up another half hour chatting with the other guests and then followed. I asked her if I could share the bed as it was the only one and she was very compliant. Within seconds of getting under the covers she was kissing me and climbing all over me. Clothes came off and hands roamed but there was no sex (we were both pretty hammered and I didn't have a condom anyway).

The next morning, rather worse for wear I walked her to the taxi rank and we talked some more. She thanked me for not taking advantage of her and we parted ways with a hug and her saying "I'll see you again some time".

Since then she's been quite aloof. I didn't get her number and the only way to get hold of her is through Facebook and I don't think she has a laptop at home as all of her posts are via mobile. I asked her if she wanted to go out for drinks the following weekend (and initially she was agreeable) but on the Friday she messaged me to say it was her friend's birthday on Saturday and she was taking her out so we would have to have drinks some other time. The weekend after that she was going abroad with her sister for Christmas.

So now we're in the present and I've invited her to my birthday party at a nightclub next Saturday. I'm determined to take things further with her as she's a really fun girl and I'm drawn to her but I'm not sure if she feels the same way about me. On the one hand she was the one who invited me to the party. She was the one who built the sexual tension and initiated the kissing/fooling around. On the other hand, since the party she's been distant and comes off as uninterested. My friend (whose party it was) said we looked good together and to be persistant because she's actually a shy and insecure girl and just needs some work, but I'm not so sure.

What can I do at my birthday party to escalate things with her? I don't want to be pushy but I want her to know it's OK to take things further if she wants. I need to convey that I'm not interested in a one night stand but would rather have something more meaningful and lasting but there's the danger that she may misconstrue my advances and take me for a player who's only interested in her for sex. Any advice would be greatly appreciated.