Is she just playing games with me?

theres this girl I really like a lot, I have never felt like this with a girl before, im happiest when im around her, she makes me want to do better in everything, im not sure if im in love with her but I think I mite be. the problem is… her past relationships were complete disaters, we started hangin around together about 4 months ago, she says she’s seeing this other guy and has been for about 4-5 months now, but has no proof he exsits, she dont know his surname and none of her family know about him. anyway some of the things she does makes it look to me like she does have feelings for me e.g when were sittin on the sofa alone se would lay on me and stroke my leg or she she would lay on me on her front and bury her head in my neck and say how she could fall asleep in my arms and stuff, she also aske me to go on holiday with her (just us 2) and I said I couldnt get time off work that soon (because I had jus started a new job) so I said to her ‘ why don’t you take lee’ (lee is her apparent boyfriend) her exact words to me were ‘I dont want him to come’. I told her I liked her but didnt say how much because I fort it mite scare her off, but she still says she’s seein this other guy. I dunno what to do because she is the first girl I have ever liked this much in my life so I don’t want to give up but I don’t want to seem desperate or end up looking stupid.

I just need some advice on what she mite think or weather or not she likes me or if she’s jus playing a game or something.