HOLY HELL!
"I did tell her in no uncertain terms that I'm hers anyway & that went better than I really expected even though there's still so much ambiguity."
Well you ruined it. Once you tell someone that they can have you, they know they don't need to earn your affection, you've just lowered your value.
All those "looks" you think she's giving you, might be misinterpreted by you.
Your only hope is to cut off all communication. Get a new phone number, pretend you lost hers (phone stolen etc). Be aloof, if you see her again, say "oh, hey how's it going."
However even that is not enough. Because you cemented yourself as a BETA.
You literally need to get with another girl and make her jealous. It along with ignoring her, IS YOUR ONLY HOPE.
Go and read the Red Pill, become an Alpha. Do some chin ups, get fit and healthy, focus on a mission. Learn guitar (sing, a musical instrument). This is literally you only hope. And if you do all of this, you may even find another cool girl and give up your Oneitis for this "she's not like the rest" girl.