But see, here's the thing with going to extreme lengths to lose weight - your body is flipping out. It thinks it's starving to death and it is. I did this once, I wanted to get into the 130's so bad that I did exactly the same thing. As soon as I began eating like a normal person again, I put all the weight back on.
Firstly, your starting weight was perfectly fine. I'd kill to weigh that much, millions of shorties like us would. You were no where near fat and I'm being totally honest with you here. Secondly, now that you've starved off the weight, the only thing you can really do is try to get back to normal. You shouldn't be working out 3 times a day, every day. Unless you're breaking up a longer workout into several smaller ones, 3 times a day is too many. Try what silverbirch said and add 100 calories onto your total every week until you reach at least 1200 a day. So you're eating about 400, try eating 500 for a week, and then 600, etc..
My guess is that it's going to be tough because your body hasn't been happy with being starved. That's the problem with this though, it's one big trap. You think you'll lose all the weight super fast and then just be okay but it's not that easy. There's kickback from your body when you do that, keeping it off and eating normally is very hard, but you can't keep eating 400 calories a day forever, you'll literally run yourself down until you die and why would you ever want to do that to your body at such a young age? One mistake like this could impact the rest of your life, please, once you figure out where you need to be and how you need to eat, don't ever use this sort of method again.