Long story short: we have been meeting each other for a while for semi-professional reasons, around two years now, although we only got close in the recent months. We have a very strong group of friends thanks to which we interacted a lot recently.
A job-related difficult situation arose recently and we have been extremely supportive to each other. We talk for hours at night about what's troubling us, we worry whenever one or the other is not in a good mood to extensive lengths. If she wakes up before me she always says good morning and ask me how's things.
I always thought of her as "way out of my league", and for this reason didn't even approach the concept of a relationship until recently: she is very fit while I am on the softer side, and I don't know what to think: she is extremely smart, intelligent, and would never reduce me down to my weight, but I do believe that looks play a part in all of this and honestly I believe myself as quite ugly. All of this didn't deter me from getting extremely infatuated with her, up to the point where she's all I can think about.
We'll have some time next week to be just by ourselves; she hates to trouble others, but she agreed without much fuss to let me accompany her at an important meeting, adding she'd be delighted to have me there.
On one side we have this wonderful friendship, and I'd genuinely hate for it to crumble. We so often joke together and talk about important things and I worry, what if my feelings are exaggerated and they end up ruining everything? Should I just make them quiet down? Of course I am basing all of this on the concept of a sure rejection, but the chance for them not liking me in "that" way is so strong in my head that I am also quite paralyzed.
But then again, a few days ago she re-posted a messenger screenshot in which I appear with a colored heart next to my name, and my brain obviously yeehaw'ed right into over-analysis: wow! a heart!! But.. is it colored because it is secondary, less important to the red one and thus indicating a strictly friendly relationship? Or maybe it's a special color (it does have some meaning for us two, would rather not explain as that'd be too sensible of an information) and thus acquiring the opposite meaning? I guess I would have understood better if other close friends of her appeared in the screenshots, as to gauge whether or not they also had a heart next to their name, but that didn't happen so I'm left with doubt.
Sorry for the rambly mess. Any suggestions and words about how to deal with this are more than welcome.
I think you already have a good start here:
Then tell her what you want, e.g., "I'd like to see if there's any romantic chemistry between us, can I take you out on an official dinner date?" Considering you two are close already, maybe you can have a deeper conversation about it; tell her your feelings and wants, and ask her what she wants out of a romantic partner (if she even wants one), and if you're in the ballpark of what she's looking for.
Also, I suggest going into this conversation with a relational mindset. You don't want to go into it worrying about what she'll say, or if you'll ruin what you have. You should be interested in what she has to say, and open to whatever she is feeling, and embrace the opportunity to get to know her better, even if you're not going to be in the picture as a romantic partner.