If you are having difficulty communicating verbally, write her a letter stating how you feel and what is on your mind. Written words are usually "heard" more than spoken words. Also, it will be cathartic for you to get what is or isn't troubling you out of your inner being which will then give you peace of mind. I say this often, communication is key to any friendship or relationship. Good luck.
You got to think in the moment when you say the words "I love you" what makes you love her? What are things you love about her? It's little things that could make us fall inlove with our significant other so let her know tell her what you like about her. ?
tell her exactly what you said here, and add that there's more you'd like to say but can't seem to find a way to say it. and you feel it's important that she knows how you feel. i'd almost bet that will start the conversation ball rolling.good lickOOPS! I truely meant to write good LUCK!! lol.