Are you sure it is all foremilk?
If you pump and get anything, and it stands, what does it look like? Because, honestly, I have never heard of anything at all like this. And I have a lot of experience. I think the green stools are more likely to be because of something else.
Weight...it depends on other factors before I start worrying.
Breast compressions...go to the pumping forum and there is a how-to link in there. Give it a whirl. You may get more milk.
Is your pump new, or is it the one you used before? If so, it might be worn out, as honestly, it sounds like you have plenty of milk.