I'd actually recommend slowing this down a bit. Fools rush in. Having a girl crush and being emotionally capable of having a relationship with a woman are two very different things. Think about this. Do you find yourself attracted to other women, or just this one? Have you ever been interested in a woman before? Have you ever had any inkling that you might be? Is this an infatuation that will pass or is this more? Take the time to really, really reflect on this.
I open doors for men and women routinely because I like being helpful. She could just be a nice person or like you as a friend. Calm down and watch for other, more meaningful signs. Ask her about exes and see what gender she mentions. Again, fools rush in, so breathe, relax, don't try to force anything, and see what naturally develops. It's totally possible that, like most crushes, this one will fade in a couple of weeks.
Not to say it never happens, but going from "completely straight" to being emotionally capable of dating women so quickly isn't that common. Don't get hung up on applying a label to yourself. Just give yourself some space and see how things feel to you. It isn't kind to experiment on another person without their consent. If something more than friendship does begin develop between the two of you, give full disclosure upfront.
