Impossible to lose weight! Help?

I'm 5'0, 103lbs (7 stone 5).

On some people that looks thin and toned, but I've got a terrible case of the skinny fats. On me, 103lbs looks chubby-- my upper arms couldn't be considered anything but plump, my D-cup boobs on a 28" ribcage make all my dresses hang really strangely, and there is just no form-fitting lower body garment in this world that could prevent me from looking like I'm wearing a bustle.

Unfortunately, anorexia left me with zero muscle tone, and I have developed (actual diagnosed-by-blood-test) subclinical hypothyroidism which appears to prevent me from building any back up. I've done weightlifting, cycling, yoga, you name it-- still nothing.

I'm trying to get back down to 95lbs, at which point my periods hadn't stopped and I had an OK amount of energy, so I know it was not an unhealthy weight for me (they didn't stop until I hit about 6 stone-- they're quite resilient), and where I looked and felt good-- my proportions were, for once, in proportion. Particularly, I'm trying to get back down to this weight /without/ eating less than 300 calories a day-- I can't say that was good for my internal organs.

In addition, I model for some Japanese clothing companies and, well, they consider me a bit... fat compared with the Japanese models. To be honest I /am/ fat compared to the average Japanese girl, let alone model, and that is really hurting my career.

These last three weeks I've been eating about 1000 calories a day, which is about 400 less than my maintenance calories (subclinical hypothyroidism; I look at food and put on 5lbs!). I've also been getting in what exercise I can-- about an hour's walking/jogging per day. Lo and behold, I've lost exactly... nothing at all. It's getting beyond a joke.

What on earth can I do, short of quit my job and spend the entirety of every day jumping rope? I'm really not prepared to just "let it go" or accept my lot and be chubby.