What am I to think about my partner

What am I to think about my current girlfriends actions. I have been with my girlfriend for 14 months now, we are living with each other and all generally has gone well.

The issue that I have is she has a general lack of passion or spark toward me. Having had a previous relationship and making many mistakes I was keen to learn and from the off I was attentive, supportive and tried carefully to create a fantastic relationship. I quickly noticed we had different styles about us, my great amount of effort wasn't very often matched by my partner's.

Over the months this has eaten away at me a bit. Smaller things like her staying up when I go to bed to things like me coming to bed with her and no kiss, or cuddle has left me very deflated over time. She has never been greatly bothered about sex with me, I'd love a fantastic sex life or for us to at least try and have one however she makes an absolute minimal effort, all this has resulted in my stopping a goodnight kiss or cuddle or trying to have sex as I'm fed up making the effort and then feeling deflated.

My general worry is that she has no doubt had a spark with a past partner and will seek that once more, she likes a good night out and some worry stems from that, the rest is a general resentment that she doesn't seem to want to try or look at addressing this. She has said sex isn't high on her list of priorities, and maybe I have to prepare that is how she is, I can't seem to help my worries and effect this is having on my own self esteem.

Am I being selfish here or does anyone have advice or ideas? I've raised the issue and she has stated low drive, kids in the house as the main reasons. I don't really know. She has made no efforts to address this or improve our sex life or the smaller things like putting me a Bit further up her que?