After going through your history, You have not said any thing about urinary symptom like burning ,frquency or pain during passing urine. Your ultrasound
examination did not show any kidney stone.But why left pelvicalyceal system prominent? some time a stricture or a reflux in urinary system
may cause recurrent infection.
Your urine report says plenty pus cells which indicate some kind of urinary tract infection
was any Urine culture is done if not ypu should go for a good sample for urine culture and sensitivity of organisms.
Some time it may be negative if taken after use of antibiotics. If organisms are resistant then you will get positive report.
Urine report is incomplete because is there blood in urine or albumin
is positive ?
A sterile culture with positive pus cell may be Renal Tuberculosis
should be ruled out.
Consult a Physician and/or Urosurgeon will help you