Scoliosis with Harrington rods looking for mattress in Vancouver Canada

Hi, I’m looking to replace my current mattress and my research has made me even more confused about what I should get.

My details:
BMI 21.9
30s with corrective surgery for scoliosis in teens, has c curve with Harrington rods so need alot of support for back
side sleeper
twin bed (fits my size best)
living in Vancouver, Canada