I Need Some Advice on Femininity

Recently, I've had a rather extreme drop in confidence due to the fact that I don't believe I'm feminine enough. I've been told that I "look like a guy" and "sound like a guy" since I was in high school, I thought that I had gotten over this, but apparently not. Even when I try to be stereotypically feminine (e.g. Wearing skirts, pretty colours etc.) I always feel like it's unfitting of me or that I'm faking something. My girlfriend tells me that I'm perfect, but it's still difficult. Do any of you have any advice?