Please don't feel under confident, you are doing fine, there is no "average" person when it comes to flying, we are all different and we all learn at a different rate. Also remember the other variable is your instructor/instructors, alot depends on their ability as well.
For a PPL people have taken the minimum 45hrs, but alot, if not most will have taken alot more than this, some take 50hrs, some 60, 70, 80 and even post 100hrs.
What will be your downfall is putting too much pressure on yourself, just relax, enjoy the course and you'll finish when you finish, it doesn't matter and it isn't a competition (it only matters when you can't afford it).
Personally I was ready for my skill test at 38hrs, but after a long row with the CFI he wouldn't let me take it until I had 45hrs (which was wrong on his part), because of this and crap weather I passed it with 56hrs in my log book. Did that matter? absolutely not.
I've had students who have taken 20hrs just in the circuit, they just couldn't get the judgement of the last 10ft, these will take 60hrs or more to gain their license. Another one passed his with 120hrs in the log book (if he was my student I would have given up instructing HAHA).
When your instructor says you are a bit behind he probably means you are not going to finish within the 45hrs, but really, it's not important.
Best advice I can give you is as I said above, just relax, there is no time limit (only a money limit). Enjoy it, because it's there to be enjoyed
