Generic Finasteride vs Propecia?

36/male with mpb/thinning in my hairline. I was prescribed 1mg finasteride and have taken it for 4 months. I've seen MUCH MORE thinning in this time frame, and, due to financial reasons, I have been using generic Actavis Finasteride from Costco instead of Propecia. I've read reports that Propecia has a better response and works better than generics without shedding--is this true? Does Actavis not work as well as Propecia? I know in theory it shouldn't but am I not responding to the generic?