I understand. When I was that age I was always sick both physically and mentally. You are a good mother. I hope both of you can get through this soon.

I understand. When I was her age I was always sick (both physically and mentally). You are a good mother. I hope the two of you can pull through this soon. Use "her" for the age of a daughter (or "his" for a son). Use "your" for the age of the mother.

I understand. When I was that age I was alway sick, both mentally and physically. You are a good mother and I hope that both of you can get through this difficult time soon.