It's in the Aster family, yes. But, there are 20,000+ species in the Asteraceae, so that doesn't really narrow it down much.
Most (not all) of the species in the family with milky sap are in the subfamily Cichorioideae. That narrows it down some, but there are still about 3,000 species in that subfamily.
At this point, I really couldn't even guess what it is (which is why I didn't say anything until now). I can say some things it is NOT, which isn't all that helpful. Sorry.