Nothing to worry.
White substance you pass might be due to passing of some salt like phosphates giving rise to this problem.
Some times in urinary tract infection
you may find this type of urine.
Go for urine check up and get report.
After report go for treatment accordingly.
Quantity of night discharge depends upon how much frequentlu you have night discharge.
If you have night discharge daily, then quantity is going to reduce due to there is no time for production of semen.
Take plenty of water.
Ok and take care.