libertarians aren't necessarily opposed to private charity, volunteering, etc
as OP indicates he is specifically non-libertarian this means he A) doesn't understand libertarianism or B) wishes to resolve disputes in a way that favors some groups above others on an arbitrary basis or C) both
if you assume political equality / non-favoritism you can't have
-taxation
(which presumes some people have a right to take the property of others but not the other way around)
-legislative decrees
(which presume that some people have the right to enforce arbitrary rules on others but not the other way around)
and therefore cannot have a centralized authority to enforce your desired social reforms and therefore cannot be a progressive
If you nevertheless remain a progressive, what gives (or anyone else) the right to determine which social reforms shall be enforced? Why do you get to be the boot and not the face? And how confident are you that your team will remain the boot forever?