From your post I assume that you and your neighbour have been friendly for a while now. She knows what kind of person you are. The letter you sent her can seem a little over-enthusiastic, but definitely she won't think you are a creep. I don’t think you have any worry on that score. Put the letter out of your mind and get on with your life. If she replies, good. If she doesn't, oh well. Don't sweat the small stuff.