I don't want to be a child minder

Oh wow thank you. I thought I would be shot down

There is absolutely nothing wrong with you for not wanting caring responsibilities. You say you don’t mind babysitting for nights out or illness and I think that is very kind and generous of you, your family should be very grateful for that. It sounds like you are fair, reasonable, assertive and boundaried which is something many on here myself included could take note of.