I'm O neg, I was told I'm.a universal donor, apparently anyone can receive my blood.
I was a regular donor for several years, in fact the Blood Transfusion Service used to send a car to pick me up from school every 6/8 weeks to take me to the centre to donate blood through a process called plasmapheresis, where I donated blood but received my red cells back to prevent anaemia. This was in the late 70s, I stopped going when I was expecting DS2.
Ironically, when I was being prepared for possible section to deliver DS2, I had to wait for ages for them to find a cross match for my blood.