Re: slow progress
You have described how training is done at your dojo (only training with someone of the same rank, not changing partners during class, etc.). Those are not typical of aikido dojos in my experience, but apparently that is how people train at your dojo. If that doesn't work for you, you need to seek another dojo. I think it's wise to be careful, however, about judging how good you are or how good anyone else is, based on only six months of training. There's a sarcastic quote I've heard -- I don't know the origin, but it goes, "When I was 18 years old, I thought my dad was pretty stupid. By the time I graduated from college, it was amazing how much he'd learned." The meaning, of course, is that a novice is not in a good position to judge someone else's abilities. But if you really believe that you're wasting your time training with people that you're convinced are inferior to you, then it is probably time to move on. It won't be any more pleasant for them to train with you than it is for you to train with them.