Inaccuracy

I'm really tearing my hair out with this.. I've made a font based on a single line, i convert that to an expanded stroke with rounded ends.. I've imported those vectors into both Fontlab and Fontographer. Both programs distort the character shape. Especially noticeable on the rounded ends. Fontographer is a bit harder to see the distortion due to its limited zoom, you need generate the font to see those details.. but at least it is more accurate than Fontlab. I've seriously tried importing as EPS and copy pasting from both Illustrator and Freehand.. I don't understand why these applications need to alter the curves. Is there a way to prevent this happening?

If i were only using the font for smaller applications it would be fine. However, i need to use this font in a massive headline application also..