THe enlarged uterus is usually either fibroids or adenomyosis (this is an ingrowth of the uterine lining into the uterine muscle). Adenomyosis can cause painful periods, but usually not heavy bleeding. Fibroids and adenomyosis are usually not cancerous, but can be painful, and fibroids can sometimes push on the bladder or bowels, making it difficult to have a bowel movement, or making you feel to urinate all the time. Neither of these are life threatening.
Many women choose to wait until menopause so that the fibroids can shrink, and perhape relieve the symptoms of pressure. As long as the fibroids are not causing you to retain urine in your bladder (you should have this checked with a 'postvoid residual test'- which can be done by your urologist or gynecologist), they are not a life threatening matter.