Hi Fana,
There are a lot of excellent videos on that website, if you poke around. Here is one on pediatric transplants for AA:
https://live.blueskybroadcast.com/bs...T=944&CAT=1090
5 platelet transfusions is not a lot. They do like to move quickly to transplant though, once you have made the decision. Blood products should be irradiated, leukocyte depleted, and CMV negative (if your son is CMV negative). All of these are important for a future transplant and you should check that your son's blood products are each time.
There were some pediatric people on this forum who relapsed after 5 to 15 years of stability. For an adult patient, 15 years would be awesome! For a pediatric patient though like your son, he will likely have to deal with this again and the timing will be less convenient (like when he is in high school or college or ?). There have been some grown pediatric patients on the forum that don't want to deal with being sick again after a relapse or going through the treatment. It is hard living with the uncertainty of the illness.
I would recommend talking to a transplant team, if you haven't already. Their perspective is different from the regular hematologist. I remember seeing survival rates of 80-90% in the pediatric population with a matched sibling donor.