Am I too young to really be in love?

I'm 14 years old. I've known this girl for 5 months now. At first, I wasn't sure if I liked her or not, but she always gave me a funny feeling. As the weeks past, I started to like her, and now, I'm so sure that it's love. I don't know why I'm so attracted to her. But she changed my life for the better. We're both Christian. I used to smoke cigarettes and marijuana and I was a pervert. But she changed all of that. We're very close; she says that she's not sure if she's in love with me. I've been infatuated many times before, but this is nothing like it. I'm 100% sure that its love, but people keep on telling me that it's just infatuation and I'm too young to really be in love. Who should I follow? My heart, or those people?