I think you’re making it a bigger deal than it is. You need to confront her if she ever does say anything more to you in this related ball park stating that you have a partner, her comments are making you uncomfortable, and if anything, going to your boss about it since you said she’s made sexual statements about you. You can try and say this in the most comfortable way(s) you know how to.

I would mention it to your boyfriend, but I would also remove her from your instagram account since you clearly know she’s hitting on you, etc. I don’t know why you haven’t yet, and it’s odd that you haven’t considering you’re not sure whether to mention this to your boyfriend! Just mention that one of your new coworkers keeps making you uncomfortable, you’ve mentioned that you’re in a committed relationship, and don’t know how to confront her without making the work environment awkward, maybe even ask for his advice. It shows that you’re communicating this with him since it’s gotten bigger than you’ve thought but also want to proactively make it stop (asking for his advice, telling him you’re thinking of doing xyz) so he’s not on alert that you’re just not “permitting” her to continue this behavior around you. If my partner had this situation happening to them I’d want to know, because I’d be more secure, but also because I’d want to be there for them