You are receiving a lot of good advice here. I just wanted to chime in that while a platelet count of 33 is low in the normal world, in the MDS/AA world, in the absence of bleeding, it would be considered okay. My doctors wouldn't consider a transfusion unless my platelets dropped below 12k, in the absence of bleeding.
Platelets only last 5-7 days, and a person can become refractory to platelet transfusions at any time. So, getting them more frequently than necessary is discouraged.
Best of luck to you and your sister!
53 yo female, dx 9/08, AA/hypo-MDS, subclinical PNH, ATG/CsA 12/08, partial response. small trisomy 6 clone, low-dose cyclosporine dependent