When I use (L)GPL license, a) I want to use their fixes and contributions to my code for free, even if they prefer not to share, and b) I don't want for them to

When I use (L)GPL license, a) I want to use their fixes and contributions to my code for free, even if they prefer not to share, and b) I don't want for them to limit my freedom to modify MY code in THEIR product. I cannot achieve my goals with MIT license.