Hmm...I'm not sure how to answer this.
Part of me want to tell you that you probably look great and only an insecure man would ever tell you you don't look feminine enough. I'd also want to mention that it's probably only you who is really noticing. However, I don't want to tell you how to feel about your own body...so I'll move on.
Vascularity is usually a combination of low body fat and genetics with muscle density.
You can't change genetics (at least not yet...come one gene doping!) and muscle density is a good thing, so your only option is to get fatter.
Unless you're underweight, or experienceing
amenorrhoea you're probably not 'underfat' which makes recommending getting fatter essentially an unhealthy option. Unless you're rocking a visible six pack, at which point putting on a bit of weight is not unhealthy at all.
However if you're not super lean everywhere else it's probably down to genetics...and that's just how it is.
on another note you may feel better if you realized how many women are working their asses off to have what you see as a problem. You're not wrong, and they're not right, just thought I'd put that in for perspective...
Good luck.