Why did you wait so long? I will say I think it's weird if a someone knows quickly that s/he's in love with someone, but to wait six years to tell her? That's just weird.

It seems she had no idea that you liked her, instead you gave the creepy feeling because you liked her.

I don't know OP's situation, but I was the girl in something that happened that could be similar. So I have an awesome group of nerd friends I play dnd and magic with and we watch movies and it's awesome, definitely something I want in my life. We're all socially capable and we're hygienic and dress ok and we're awesome and not judgemental. Their friend Donny, not so much. He'd been friends with them since long before I joined up and was dating the only other girl in the group. She was my friend, and introduced us the first time we hung out all together. The very first thing he did was pull me aside and tell me that years before he'd had a dream about a girl like me floating naked in front of him, and so we must have a common destiny. Yeeeeaaah, it went downhill from there. So he's a basement dweller who didn't use deodorant and he constantly belittled his girlfriend, my friend, for not being good enough. He'd call her stupid, ugly, inattentive, and I hated that a$$hole. He constantly bad mouthed our friends to me, saying that they were beneath him, even though he brought nothing to the group. He wasn't funny, interesting, smart, and he couldn't carry a conversation that wasn't about transformers. I started insulting him viciously to try to get him to leave me alone after he tried to spy on me showering at a comic convention where we all shared a room. My friends separated us and told me to be polite to him because they all had history. I was, I hated him but loved our friends. It was fine till we went to a different convention and he decided it would be a good idea to ask me out in front of everyone and say that I was the only one worth anything (of our FRIENDS) and that since I was the most beautiful girl he knew I should be with him. I told him he was an awful worth less creep and I hated him. He asked twice more. Some people build up a fantasy relationship and are shocked when it turns out to be nothing like the reality, especially nerdy guys towards nerdy girls

You deserve it. It is absolutely creepy to blurt out that you love somebody out of the blue after six years. Think of how that must look and sound from their perspective. Next time just say you enjoy hanging out with the person and ask if you can go out sometime. They will get the message without you coming across like a crazy person.

She's not worth your time OP

If you wait six years to ask someone out you are a creep. You're not in love with her, you have a creepy obsession with her.

She's probably felt you pining away for her. That definitely makes a woman uncomfortable.