Bloating, and fullenss in the bladder could be serious. Then again, it may not be, so I will not scare you and give you a diagnosis, I am not a dr. I will stress the importaince of seeing your dr. about it though. You need some testing done.
You have not given enough information. Are you drinking enough? Do you have any pain or burning when you urinate? A trip to your health care provider may very well be in order, but do be sure you are drinking enough water!
Actually you have not given enough information regarding your condition. How old are you and do you have increase frequency of urination or just reduced amount you pass only? Do you take enough fluids ? Do you have loss of appetite and loss of weight?After you pass urine do you feel that you have not passed enough? How is the stream do you pass intermittently or pass continuously? Have you ever passed blood with urine? These are some questions that comes in to my mind right now. So it is better to seek for medical advice.