I'm on a 25 day cycle & i'm now 3 days late. i feel pressure above belly button & have sharp pain off & on. how long should i wait to get a test ?

Not too long!: Three days late is not extraordinary; however, it is 3 days late... Any cycle can have some variability to it, so i would give it a few more days. The problem is the intermittent pressure and sharp pain, though. If you have symptoms of pregnancy (nausea, breast enlargement/tenderness, weight gain, ) then take a pregnancy test. Worst case scenario is a tubal pregnancy, so keep your antennae up!