Frequent Urination problem in 9yr old boy

My son is 9 years old and he is suffering with frequent urination (micturition) and this problem is since begining. When we consulted with allopathic/homeopathic or ayurvedic doctors we have been told to wait until he is 8yrs old as in most of the cases this problem subsides by itself then. But when now he is 9yrs and still his problem is as it is, that concerns us most.

symtoms:

1. He feels immediate urge to pee. Everyday he goes 15-20 times and sometimes more.

2. Pee color is normal.

3. It is scanty sometimes but not always.

4. He does not have any pain or burning.

5. Since he feel this urge so immediate that most of the times he wets his undies. And because of that he starts stinking after a while.

6. Upto 7yrs. he was having a bed wetting problem but last 2yrs he has improved upon it and wakes up whenever he feels its urge. Now only 1-2 times in night he wakes up to pee.

While travelling we carry bottles to help him pee in them.

Any advice on this one?

Thanks,
Kailash