Feeling Inferior

It's a strange position I am in and it's hard to explain. For the most part at home and while the children are with us I am in the role of parent and do all the things that come with that. But happens at times when we are out with the children's mother? I know I'm probably overthinking it but it's at those times that I feel inferior and reminded that I'm not a real parent. I know I'm not a biological parentbut I find it hard to switch between roles when their mother is present. I'm sure as I get more confident in this role it will be easier. I should also say that things with their mother are pretty good at the moment. Communication is improving and I think there is more acceptance of the whole situation and all it's complexities.