you didn't mentioned whether it is your first pregnancy
The possibilities for your pain are,
grows it will become dextro rotated, so because of pulling of round ligament on left side pain may be felt on left side.
in case of prior cesarean section adhesions will be there which will cause pain with movement this can radiate to back.
As uterus grows it will exert pressure on bladder which may be responsible for your urinary symptoms.
Chances of urinary tract infection
is also there.
You consult your gynecologist once get examined and go for urine analysis.