Uncomfortable being feminine....PLS HELP!!?

I grew up with 3 older brothers and growing up I was a bit of a tomboy. I've been told a lot that I'm very, very pretty but that sometimes I can be a bit overbearing and self-protective. The truth is that I feel VERY uncomfortable being feminine or letting people see the sensitive side of me. I don't ever wear tight fitting clothes or low necked shirts and I have a hard time doing things like wearing heels. This mostly stems from that fact that I feel extremely incomfortable when men look at me. I'm 25 and am single so this is becoming a huge problem. I'm at a point in my life where I'm becoming a woman and I can't attract men without feeling sick. Doing things like moving my hips when I walk or flirting is like I would rather jump off a cliff. What is wrong with me??? Any advice would be helpful!