Used to be a realtor. While I hate realtors your doing it all wrong. Realtors have a thing called fiduciary obligation to clients which means if you don't have an agreement (contract) with them then they do the bare minimum.

Find a realtor you like and have that person schedule all the apartments on YOUR time. Hopping from one to another, to another, to another is time consuming and the realtors could be doing a million things. Your going to most likely pay the broker fee no matter what. So get a realtor to do the work for you.