Well, first thing is first. The Wiccan Rede only applies to Wiccans who actually believe in it. Also, the Three Fold doesn't apply to everyone. It only effects you if you think it does. Also, it's honestly better if you create one yourself. Try something besides a state of total love. A honey jar, maybe? It's an idea to "sweeten" the person you like towards you. That might work well, if you wish to use it.
Real magick isn't anything that you see on TV. There's no potion that will have someone completely fall for you immediately, there's no spell that will wear off suddenly if you don't cast it right. None of that is going to happen.
If you really want her to try and fall in love with you, is talking to her. Form a relationship. Be there for her, care for her, and all that jazz.
[insert cliche line about finding someone that's right for you]
And sometimes, no matter how you want it badly enough, the Universe doesn't think it's right for you. She isn't the only girl out there.