No one can tell you when you should solo.. There really is no average either...
When a person solos is dependent on their ability to 1) be safe and 2) fly the maneuvers and 3) land.
At less then 6 hours is not likely enough time to have mastered the required pre solo maneuvers that are dictated student pilots be proficient in.
20 to 25 would not be considered high, I would ask your instructor if that is the minimum time you must have before he signs you off to solo OR is that the average he has seen others do it in.
I usually see people solo in 10 to 20.. Again, this all depends on how fast they learn, how well they do flying the airplane and how much of the required knowledge they have.
Not sure I would be pressing to solo at 6 hours or feeling that the instructor is "soaking me"... If it makes you feel better fly with another instructor or call and talk to another instructor where you can go into more detail about your 6 hours you have already..
I can tell you what I look for before soloing a student.. If I'm sitting there completely board. With nothing to do I ask myself if I would put my family in the plane with this student.. IF I'm board and the answer is yes.. Then its time for this student to solo...
Hope that helps some, I would need more information to give better advice.