Grarena, you are doing very well. For us "old guys" ( I'm 69) continuous training gets to be required. Starting where you are, you will see substantial improvement. Couple of things that might help. For dynamics, a neck weight is much more effective in balancing your buoyancy than a weight belt. You can make your own, find a source of lead pellets (dive store). some bicycle inner tubes, plastic backpack buckles and electric tape, easy. Lots of videos on how to put it together. If you mostly train dry, the new book, "Longer and Deeper" by Yaap Verboss is an outstanding investment. He goes into the physiological "why" as much as the "how to". If you really get into it, Eric Fattahs ebook is another great investment for the serious diver.
Apnea walking is excellent training for real diving, just walk on something soft. As you start to push it, the odds of falling down rise fast.
New Orleans has to be my favorite city. Oh, the food! And everybody ought to experience Mardi Gras once. I grew up in Mobile and thought I knew Mardi Gras, until I went to New Orleans, oh my!
Oh yeah, old is an advantage in this sport. Slower metabolism means longer breath holds I'm a whole heck of a lot better diver than I was at 20.