Why can't I understand love?

There was a time in my life where I thought that love was a magical beautiful, unexplainable thing that would be perfect when I finally found it. And I finally did. I am 17, and I fell in love with my best friend back in march. Everything was great, I admitted my feelings for her after awhile, and then she admitted she had feelings for me, and I was so happy that we could finally be together, and the fact that we were in love made this so much better. I was completely happy without a doubt. But I am a very intellectual person, and I put a lot of trust into science. One day, in my curiosity, I went online to try to learn more about my new feelings of love. The first site I went to was, evidently, wikipedia. I read things on there and several other websites about how love is a physiological thing caused by hormones and pheromones. This seriously started to freak me out, because I didn't think it was a special connection anymore, or that it would last very long. She and I had plans on getting married, and I was all for that before and in a way I still am, but I am terrified that as time goes on, "the hormones will fade" and I won't love her anymore. But I don't want that to happen at all. She is amazing and I love her so much and I would be so excited to spend the rest of my life with her, but I can't get this unconscious feeling out of my head. It has been making me miserable for months. When I'm with her, I feel great, and I am so amazingly happy, but the longer I'm apart from her, the more these feelings come back and the more I doubt my love. I need help getting past this.