Good morning, @crhilston. In another reply you wrote that you’ve recently found out you have acute myeloid leukemia (AML). I also had this diagnosis 4 years ago. I’ll be honest with you, this one is a bugger.
I think this informational article from our Mayo website will help explain what’s happening with your blood better than I’m able to do… Here’s an excerpt:
“Your bone marrow produces blood cells. Acute myelogenous leukemia occurs when a bone marrow cell develops changes (mutations) in its genetic material or DNA. A cell's DNA contains the instructions that tell a cell what to do. Normally, the DNA tells the cell to grow at a set rate and to die at a set time. In acute myelogenous leukemia, the mutations tell the bone marrow cell to continue growing and dividing.

When this happens, blood cell production becomes out of control. The bone marrow produces immature cells that develop into leukemic white blood cells called myeloblasts. These abnormal cells are unable to function properly, and they can build up and crowd out healthy cells.”
https://www.mayoclinic.org/diseases-conditions/acute-myelogenous-leukemia/symptoms-causes/syc-20369109
While no one can predict your life expectancy with this diagnosis, what I can tell you is that once the abundance of defective, immature cells start outnumbering the healthy cells, if not treated, this condition can develop rapidly.
Taking into account your age, your hematologist may feel that some of the more aggressive treatments aren’t appropriate. But you may want to ask about potential chemo treatments or abrogating drugs that can slow the progression of the proliferating cells.

Illnesses like this can come with a lot of questions so please, don’t hesitate to fire away if anything comes to mind that you’d like to know. I’m here for you anytime.
What has your hematologist discussed with you?