Why I just have 1 wing out

I'm "born" with a couple of wings -yeah...born's wrong XD... that's more "dead"-.
One day, as I was hunting, you know I was really hungry, I wanted blood so much that I didnt care about my own security.
I went out, probably on a "hunting-party" of some crazy vampire-haters, with a simple scythe as only weapon, and with my boyfriend, an handsome male vampire.
So I killed about...erm... I think 4 people. The last one I bit yelled so loud when he saw me, that those vampire hunters knew where we were.
My boyfriend said to me "Don't stay here. It's not safe, I think these ones aren't easy to fight. I don't wanna take any risk."
I screamed, while sucking another dead neck : "No way!!! I WANT more blood, go back home alone. I'll follow you later."
He was getting away from me when I heard him scream. He had been shot. It wasn't a silver bullet, otherwise he would have been killed. It was something else. Anyway...something bad for us : He was hurt, and people like us aren't hurt so easily.
One of the hunters came closer so I hid myself. He said to him that it was a "torture bullet", specially done for vampires of our kind. A bullet spreading liquid silver in the body. As he had been shot on the leg, he was going to be dying for a long time.
My dear couldn't stand that pain, so he yelled, asking me to kill him.
I cried inside, wondering what to do. The hunter said to my boyfriend that he'd die anyway.
I was so angry, I would kill everybody around me.
Well...I did it.
I jumped out from my hiding place, and, closing my eyes, I killed my boyfriend first. Then I killed all the hunters I saw, too, cutting off their heads and dancing on their guts, playing with their flesh and licking all the blood I had on my hands.
Unfortunately, there was an hunter left. I hadn't seen him...
I spread my wings, trying to fly away, but he shot me before I could leave.
He shot me on the wing.
It hurt. Really much.
I fell down, faking I was dead. So the last hunter went away.
Then I didnt know what to do. If this "poison"reached my back, I'd probably die.
And I saw my scythe on the floor. It was my last chance. I took it in my wrong hand, and cut my wing.
...
...I don't remember what happened next...