You've done 4 hours. You really cannot make a judgement that you CANNOT fly after 4 hours. How long did it take you to learn to drive? I seem to recall at 17 I had stacks of lessons.
My philosophy was that after a few trial lessons, I really ENJOYED the experience so I was going to give it a go. I was VERY daunted by the theory (initially) and scared myself to death reading lots of the books and stuff.
After a good few lessons whereby I was handling the aircraft, I began to calm down and feel more comfortable - but I had real problems landing - never consistent - sometimes driving into the runway, sometimes (mostly) flaring much too high. Then one day it just clicked - and its a bit like riding a bike - it will stay with you.
Try not to worry too much about the end result now, unless you are really doing the course on a very tight budget - I didn't complete in the (then) 40 hours as I had decided to stretch the whole thing out and enjoy the learning experience. Some of the 'johnny's' at the club wanted to finish in a week and actually ended up as not so good/safe pilots (IMHO).
In my day (not that long ago), solo was expected at about 10 to 15 hours of dual. Perhaps you need to have a good chat with your instructor (you do only have one instructor & you have hit it off, haven't you?) and tell him your worries. And get a full debrief after each lesson. Then when approaching 10 hours or so, get him to evaluate where you are towards going solo and compared to the average for the club.
I would also urge you to insist on 1-2-1 instruction with the same instructor. Chopping and changing instructors doesn't help as they will each want to revisit what the other has done with you. 2 steps forward, 1 back etc...
Keep at it. If you REALLY want to fly, then you will be able to.
Good luck.
Mark.