High School "Relationship"

I am a senior high school student in Australia. Male if it helps. I am usually really quiet, if you ask my small group of friends I would be considered creative and unique. I am a career driven student and definitely not attractive. I never really connected with my grade at school and always felt like an outcast and have never had a gf before.

When I first started high school, I met this girl, she seemed really nice but I wouldn't even consider us as friends. We just knew of each other. Then in grade nine we started to get really close as best friends. We would walk with each other and talk about school.

This was fine until last October when we started to become really close. We started to hang out with each other a lot more, she met some of my family members, we have gone out and eaten breakfast together many times and there seems to be this tension. Every once in a while, when the world gets silent we kinda just stare into each other's eyes but we immediately break the tension off. When it gets awkward we tend to start talking about random stuff. We even buy each other holiday presents (Christmas & Valentine's Day) which she asked to do. We sometimes also just hang in her car and listen to music. Sometimes we text each other goodnight and sweet dreams.

I really don't know what to do. I have had feelings for her for a while. I asked her friends about her and they said 'she is a really good friend'. She has mentioned in the past that she doesn't want to be in a relationship while in high school but that was years ago. I wonder if she has changed her mind. I don't want to really ask her about it because maybe she always considered us to be friends and I don't want to loose a friendship. She even asked if I wanted to meet her older sibling which at the time she asked I was busy so I declined. Many people we know ask if we are dating or like each other, and I just say "ohhh nooooo", (this includes teachers and other students).

Can you please help out?