It's killing me inside?

I recently fell in love with my sister's friend. We've known each other for year. I'm a 6'1'' guitarist agnostic and she's a 5'8'' dancer (ballerina) Liberal Quaker. She's 14 and I'm 16. We just spoke more and hung out more, basically three days of dating. We started the first day with the beach, we walked six miles to a pier (lol didn't know it costs a buck to get on) and then we walked 6 back. We really got to know each other then. Her Dad and his friend drove us home, I took her to my house (three doors down and across the street) and I cooked her breakfast for dinner, something she loves. We cooked together, ate together, and spoke more. The second day her dad took us to marina's and stuff to get boat supplies, we were left in the back of a Ford F-250 together and we leaned close together and sat there. I looked at her and she looked at me and we kissed. Her dad caught us, didn't even care. Our parents have been friends for eight years, he loves me. Every stop we made we kissed, and when he was driving we held hands. When we got home we watched a movie together (my parents were in the room too) and she and I held hands again. The third day I didn't see her as much because she was with a friend, that's cool, her friend and her friend's mom brought her to the dock where I drove the boat to, and she got in, we went for a short drive and then she had to pack up and go back to Pittsburgh, Pennsylvania. She used to live near us and visits every summer, she's going to boarding school in Iowa (a Quaker school) and It's killing me. Her not being here just feels like somethings missing. Like part of me died inside. We did everything together and became so close, told each other about our not so stellar (horrible) pasts. Bottom line is I hugged her goodbye and didn't get to kiss her goodbye. She means so much to me, I love her. I miss her so much it's actually depressing. I probably sound like a sap or something, but does someone have ANY advice? I'm dying here!!!