Hello and welcome to e health forum.
At the age of 85 yrs, it is common for the bone marrow to slow down and this results in low blood cell production.
Based on the description you may be having aplastic anemia or Iron deficiency anemia which is more common at this age.
The blood that has been transfused will be based on the hemoglobin levels in your body.
It is common to have symptoms of palpitations and anxiety after blood transfusion, due to the excess volume of fluid in the body. But these are transient and will subside as the excess fluid is excreted from the body.
You might consult with your treating doctor who can explain you the proper findings and clear all your doubts.
I hope this helps.