I Am A 47 Year Old Healthy Woman. For About

I am a 47 year old healthy woman. For about a month now I have been experiencing an unusual (hard to describe) pressure in my lower abdomen - it seems to worsen throughout the day. I seems as if there is something putting pressure on my bladder. At the beginning of January, I went to the doctor because I thought maybe I had a UTI, results came back negative. Any idea what might be causing this pressure? I am not experiencing anything that would be considered pain, it's just uncomfortable.