If the tech on babycenter said she couldn't see a nub, I'd believe her--she's really good, really experienced, and honest. Much better than what people on IG are saying for sure.
FWIW, I don't see a nub, either. If you look at this site, Embryo Development external genital sex organs - angle of the dangle boy or girl ultrasound gender scan - Baby2see or google "nub theory" for other places that have very clear pictures, what you find doesn't look like EITHER what butterfly circled or what you circled. I think your images are not clear enough to tell from, or the angle of the shots is not just right.
So I am still very much holding out hope for pink for you--with those images, it's just too soon to tell.