CRF150F softer spring?

Does anyone make a softer spring for the Honda CRF150. My girlfriend just got one and i am trying to lower it for her. She is 5'3 i think, and i already backed the rear shock down, almost all the way to the point where thier is very little rebound, i dropped the front in the triple clamps an inch, and i put a lowering link on the suspestion. She weights like 95 pounds so i think a softer spring would help her out alot. But i can only find heavier ones.

Thanks,

brent

Its not only to lower the bike, she is a beginner rider and only weighs 90 pounds so the spring barley moves and she is not going to be doing jumps or anything extreme. Right now the way i have it setup is the preload is so backed off it doesn't rebound. So i think if i have a softer spring i can crank it down better so it will have rebound and she will still have race sag.