What Causes Uterus Swelling, Heaviness And Pain, Discomfort, Tissue Loss During Urination?

Hello, I am wondering why it seems I have pain and discomfort since I've had my child 6 years ago. I've been to my family doctor because of loosing white tissue when urinating but nothing seems to be showing up or takin seriously. As well I feel as if my uterus is swollen, heavy and sometimes when sitting my pants will put pressure causing pain, feeling as if something is moving upward. I feel helpless and tired of asking my dr. What this could be. I'm starting to feel like it's all in my head. Please help clarify these issues.