Is it normal to have minute amounts of urine left over/ still trickling immediately after urinating?

No. The most common cause of post-void dribble in females is urine tralled in the introitus and vagina due compressed labia majora. Best avoided by spreading the thighs widely with urination, that means pulling panties down to the ankles. In males it can be due to an elastic waist band compressing the underside of the penis. This can be cured by using the pant fly or pulling pants and underpants low.