I agree with everything that's been said. Do NOT worry about whether or not you're learning quickly enough, worry that you're learning the right things.

It took me about 20 to 24 flights on the buddy box over a 2 to 3 month period, but my instructor taught me well. Proper use of rudder to coordinate turns, how to land in a crosswind, how to do rolls and loops....

I'm an instructor now, and try to duplicate the way I learned. I do get frustrated with a student every once in a while, but only with the ones that don't seem to want to listen when I explain what I expect from that session. I'll say something like, "today I want you to try to do figure eights while maintaining a consistent altitude", "we'll start by flying downwind, then entering a left turn towards ouselves, followed by a right turn....". Only to have the student fly repeated right hand ovals, with me saying, "remember? Figure eights?" Then, "How about another one?"

Anyway, now I'm rambling.

My brother was solo after his first flight. (I was both proud and embarrassed. ) I've had students take 30 or 40. It doesn't matter to me how long it takes, as long as the interest and enthusiasm to learn continues.
Dennis-