What is wrong with me? How can I stop feeling insecure about this?

Hi everyone and thanks. I think I have a problem and I don't know how to fix it... I have a girlfriend who loves me, and I love her. She really is all I've ever wanted in another person. The thing is, everything is going very well, and has been for some time. Recently we were talking and remembering how it all started, and she was talking about how at the beginning, when I started to like her, she only thought of me as a friend (which, before her, always happened with every girl I liked). She remembered how at some point I told her that I liked her and she said that she wanted to keep things like friends and then see what happened, and how she was also thinking of me as just a friend (she never told me this before); and then how she changed her mind. And ever after she said that I've been feeling weird. Instead of feeling happy that I "escaped the friendzone", I feel weird... Somehow I feel rejected and insecure all over again and I don't understand why!! I'm feeling the same way as if she was "friendzoning" me all over again, even though she's not! I feel like it's all some sort of lie or something... What is my problem!? How can I stop feeling like this?