Help!!

What do you do when you like someone but they think you dont, and you try to give them all the hints and let them know u do...you see i am very interested in this girl but she doesnt beleive i like her she thinks i dont want her and im not interested, i havent been with anyone for over 2years and i find it hard to get the confidence up to say how i feel. Every time i go to say it i choke and say it the wrong way and then she takes it the wrong way no matter how many times i tell her she has taken it the wrong way and that i am finding it hard to bring the right words together.....i need help i dont know what to do, also she thinks we are too different...but isnt that the point though? if we were the same there'd be no mystery, no passion no fun or feeling in the relationship. I really like her an i need to tell her how much i like her, i need to tell her she makes me weak at the knees and tht she makes me feel like i could do anything. She is like a warm breeze on a nippy afternoon and i am freezing and she wooshes up with a huge hug and warms me...(if that makes any sence) I need to let her know ....but she says the moments gone....is it....really.....can the moment go if you like someone that much? Please help me.....someone. She makes my heart skip a beat....it hurts so much that this is happening that she thinks i dont feel this for her......even after i have tried to express it.... :(