I know what you mean about A times and sleep cues! It does get harder as lo gets older. My DS2 is pretty easy to read but with DS1, in order to figure out A times at this age, I had to just start trying them. When one was successful, I would try repeating it and seeing if it kept working for him.
Also, I cannot quite remember his age, but I do remember that we were at a point where we were struggling to get good naps, and all of a sudden we had a day where our schedule was preventing him from doing 3 naps (I tried AP but it wasn't working), and he took 2 good naps. From that point we mostly did 2 naps and that's when thins really got better for him. I don't know if that might be something for your lo? (it could be totally the opposite and he needs even more sleep so I don't want to declare that this is the solution, but could be worth a try??) 6 months seems like the average age for 2 naps.
The dummy is also tricky. I am not a dummy fan either, and am kind of shocked that I have a nearly 3.5 yo with one! (Thankfully, he is just about ready to let go of it) but at a certain moment I felt like it was the way lesser of the evils being presented, and we had to choose one. That may also be the case for you guys, so I wouldn't kick yourself for keeping it, nor would I wean at 6 months unless there is reason (i.e. you don't think he needs it anymore or it is interrupting his sleep). BW is about listening to his cues, so IMHO if it seems like your lo is being soothed by the dummy and it's helping his reflux, I would keep it and try to get one of those little cloth things that attaches to the dummy so your lo can find and replug more easily.