Frequent Blood Transfusions

I'm a 73 year old woman. I'm somewhat overweight. While I have always been somewhat anemic, I have never smoked and am a non-drinker. During the past 5 or 6 months, I have had to go in for blood transfusions every 2 weeks. I'm always feeling weak; however, the doctors have no diagnosis for my condition. Most recently I was told that I should expect to have to continue with the frequent blood transfusions for the rest of my life. A legal professional (unrelated to my medical condition) informed me that I should ask for a "differential diagnosis", but I have yet to see my physician again.
Any advice would be appreciated. The Dr did mention "leukemia" at what point, but there is no current diagnosis of that for me.