Having Frequent Urination. Do I Have Urinary Bladder Infection? Urine Test Normal

Hi I think I have a bladder infection it has been going on about 3 weeks now I am susceptible to cystitis , I went to the doctors last week but my sample came back clear, since then I thought it was getting better but seems to have come back again. I feel like I constantly need to pass urine and although it doesn t burn when I do go I feel uncomfortable afterwards just like I need to go again!