I'm in an ambiguous situation and would appreciate some advice
I (18M) started to get to know a girl (18F) in one of my classes about 4 months ago (we're both seniors in high school and are close to graduating). I got to know her a little better in school and liked her, so after a month, I decided to ask her to be my date to prom. I did this in-person and she's a little more introverted, so she froze up and didn't really know what to say. I told her she could think about it and left.
I assumed I was rejected and was obviously disappointed, but I still enjoyed being around her, so I decided I would be okay with staying friends, and I never brought it up again. It was pretty awkward for the first week afterward, but I guess she wanted to be friends too because we ended up getting a lot closer over the next few months, much closer than we had been before I asked. She invited me to come to two activities she was doing (and I did come to one of them), we got to know a lot more about each other's interests and personalities, and we spent a lot more time talking alone together during school. I can give more detail on exactly what we talked about/what the activities were, but I don't know if that would be helpful so I'll leave it out for now. At this point I still assumed we were friends, and 3 months went by like this.
Today during one of our conversations, she suddenly told me that she realized she never actually gave me a verbal answer to my prom request. She said that she thought it was really sweet of me to ask her, but she had already promised to go with one of her female friends who is apparently going through a bit of a rough spot in life. I was very confused why she brought this up, since I had already assumed I was rejected after 3 months without an answer. She said she forgot to tell me, which I'm not sure I believe since she has one of the best memories of anyone I know.
I'm now very confused about where I stand with her and what she wants. On one hand, maybe she felt bad about not giving me a response and wanted to give me some closure, even if it was after 3 months. On the other hand, although I felt bad about not getting a response, I had accepted my rejection and moved past it with her, and I never once brought it up myself. I can't understand why she would bring it up just to reject me again in a much more open-ended, ambiguous way than before, albeit in a softer fashion. A couple days before this, I noticed her staring at me a lot more in classes, and she's gotten a little more comfortable with touching me on my shoulder or arm to get my attention as of recent too. I understand these are romantic signals women sometimes give, but it's still unclear. Is she trying to soften the rejection to get me to ask her out for something else?
I'm okay staying friends with her if that's what she wants, but I would of course be okay with dating her if that's also what she wants. I'd appreciate any input or advice from anyone else who might have a better read on this than me, and if there's any specific questions that might help with interpreting this, I'll do my best to answer them. Thanks everyone.