When i finish urinating, i don't feel empty. i wait and a few seconds later, more drops come. after 20 mins of this, i get up, unsatisfied. doctors here said it can be an infection, but urinalysis was clear. afraid of cancer. what can it be?

There are several possibilities that can cause this problem. Among them is a urethral diverticulum which is a sac or bubble between the urethra and past the bladder that contains urine which release when you stand. The roof of the vagina and the floor of the bladder/urethra are "apartment" dwellers. A Gynecological Urologist can do an in depth investigation when you make an appointment.

Probably not cancer. Try to stay hydrated. Cranberry juice some times help with the irritation. An infection may occur . Follow with your PCP.

Urethrovaginal reflux is most common cause of post void dribble in females. Urine flow is blocked by closed labia so that urine fills vagina before it escapesfrom between labia. Widely separating thighs when urinating can correct this. Other causes can be bladder or urethral diverticulum (outpouching) or ueteral reflux, which fills when urinating then releases urine at end of bladder contraction.

Again, not sure a meaningful answer can be given here without other data: Age, sex, medical history, etc....

see a reputable urologist