It doesn't sound like you are doing to badly at all. The trick is to make every lesson an learning experience. Okay, that might sound a little stupid but heres what I mean: If you have a what you percieve as a poor lesson and some aspects don't go as you would have liked, you will still have learned something (even if it is how not to do it).
The second thing to consider is your perception. At present I have a couple of extremely gifted students. However, I am still able to criticise their performance at the end of each flight, because there are always things that could have been done better (and that doesn't change even when you have a licence and experience). But I'm sure to point all the positive aspects as well, as it seems your instructor is doing.
So, if overall your instructor is happy take his word for it and don't beat yourself up, just learn from your mistakes and try again. As backpacker says, there's a 45 hour course minimum for a reason.