Do I have an eating disorder?

I weigh 119 and I am 5'7 . I restrain my food sometimes where I will only eat like 300-500 calories a day and on some days where I eat a lot I eat as much as I can then I throw it all up. The purging is on and off but when in do do it it takes a while be because the inside of my throat feels swollen . It takes a long time and I barely throw up anything but after that my heart beats really fast and I get a panic attack which makes me cry. The feeling of throwing makes mr happy after and before the panic attack I feel happy because I want to lose weight . My hair has started to fall out more easily .an my nails are becoming softer and they break more easily . The weird part of this whole thing is this makes me happy because one month I would drop a three pounds every week I want that to Come back .