KKRRHH, welcome. I know a lot of people that are bipolar or depressed ended up in the mental health profession. Their first hand experience gave them the understanding to help others better. Don't question it because it is something you can become good at.
Would you go to a dentist that never had a tooth ache or pulled a tooth? Of course not. Think about it like that and use your weakness and turn it into a strength which is what you are doing. tc