I understand the tired mommy thing all too well! It was that long that I was in your shoes, but guess what.... the time sure does fly. I would do the dreamfeed tonight, although your lo slept through, it is good to establish it, who knows.... maybe he will sleep through until 7am this morning, but more than likely not. It's a good thing to stick with if you lo takes it well.
I'm not too sure when the other cluster feed should be and whether you should extend the nap by 45 minutes. If you posted a sample routine, it would be easier to help you with.
I too found it hard to interpret cries, but using EASY helps you learn them. Your lo still has quite a need to suckle at that age, so if they are comforted with a paci and don't seem hungry (I guess signs would be that they are settling back down, etc) then it is ok to go with the 3 hours. But some mamas need to nurse every 2 hours until maybe even three months, so if you think he is hungry, nurse him and see how long she nurses for, this will indicate whether they are doing it for comfort or because they are really hungry.
Don't worry, it takes a while to start recognizing everything. Trust me, I was not a natural, but BW does help you become much better and then you can "fool" ppl into thinking you are.
I hope this helps, please update us and let us know how else we can help.