i think you answered the problem yourself there. You had live rock that was established before, and may have been genuine live rock straight from the ocean, now you are useing live rock that you have bought, which most likely has been sterilized and cycled. Its never the same as it dosnt have the variety of bacteria in it as it would from the sea. I still have the proper living rock in my system that I first got in 1976, its still covered in small clams and critters, and even after all the years new things just appear!!.I started out with a much different system (nano, different lighting, dry rock), and have gradually moved closer and closer to my old setup. I now have the same size (~60g), similar lighting (T5 and LED combo, used to be just T5), added established live rock. None of that has worked.
I might have just gotten very lucky the first time around. I bought live rock from a guy on craiglist who had an established tank. I got a BTA as a hitchhiker that apparently didn't like that guy's lighting but LOVED mine, as it became as large as a dinner plate and split many times. Basically, my first tank was effortless for me, probably in large part because of inheriting someone else's established rock. I tried to emulate that success by buying established live rock again, and all it has gotten me so far is an infestation of hydrozoans that are taking over.
I would be patient a while longer and let your system get more mature, then try again