Insecurities and Abuse

Thursday in WS capstone, I realized something. People really don't see me as I am. My strong opinions and blunt way of expressing them apparently give off an air of confidence and security. But the funny thing is, I am not secure at all. If it wasn't for my opinions and how much feminist research I do, it would be more obvious, that I am one of the most insecure people ever. I have a rule that I use in my feminist classes and that is the trinity of knowledge: 1.) Know something 2.) Know what you know 3.) Know what you don't know. And with that you can easily sail through any class or argument.
But as for my insecurities, to start with I have terrible body image. I mean you dont have an eating disorder without it. I cant stand going out somedays because I dont feel I look good in anything I own. Occasionally, nights like last night happen where I wore what I planned and I felt amazing, people kept telling me that I looked good and for one night I actually felt beautiful and was not insecure about how I looked(only about how I was dancing). But on the other hand I received flowers the day before from one of my best friends "because it was beautiful people appreciation day" and I still didn't feel pretty at all.
I am also rather insecure when it comes to dating/relationships, but not about the other person cheating or anything else, but about whether I am good enough or why am I not good enough? This is how I end up in bad relationships or unhealthy attractions. Often I end up with someone/or liking someone who initially makes me feel special and then I beat myself up when it doesn't work or I no longer feel special. This goes back to the eating disorder thing. If something goes wrong or even if its just not right/never was gunna be right, I feel that it is my fault and I blame myself, always attacking my looks first and then everything else. I also have a tendency to fall for people who treat me like shit. Dont know why, I just do. But I would have to say my most abusive relationship is with myself.