Feeling guilty

Hi everyone! Im looking for advice or just words of encouragement. My fiancé and I were thinking of potentially trying for baby #2, but I’m feeling so guilty about it. Back story- we have one child, he’s 4 years old. In July of last year he was diagnosed with leukemia. He is in remission now but this past year has been hard on him and us. I I feel so guilty for even wanting to give another child my love and affection even though he’s okay now. I don’t want my son to feel sad when I can’t give him my undivided attention all the time. The thought of growing our family makes me so happy and I think he would be excited to have a brother or sister. Idk I’m probably just overthinking things