What reference pics do you have? JB's right, there are definitely some kinks in there. If you want some good references, head on over to
Ex Astris Scientia's shuttle gallery. He has photos of the studio model.
Here's what I see that's wrong:
1. Your side windows are about 2 times too big.
2. The pylons flow smoothly into the sides of the fuselage.
3. The pylons flare out before connecting to the nacelles.
4. The bussard collector windows need to be longer.