My last period due date is oct 30.my cycle legnth is 26 days.I am passing 27 days,I have a heavy back pain and frequently urine.I had a urine and blood test yestrday bt result was negative.can I wait thepossitive result?

Give it about a week to see if your period is just off a bit, which can happen from time to time even if it hasn't before. If still no period, try another test at that time if you think pregnancy is likely. You could also ask your doctor about a qualitative blood test, which will pick up a pregnancy sooner than a urine or a quantitative blood test, which it sounds as if that was the sort that you had done.