Let's answer the "Am I an expert?" question once and for all.
If I say you are an expert, you are. If this or that person groups you with other experts to answer a question, don't deny your inclusion. Don't make excuses. Smile widely and accept it.
I used to argue when people branded me with expertise. But you know what? They were right, for who am I to say they were wrong?
... unlike the above video, I argue you shouldn't declare yourself an expert without someone else calling you such in a LinkedIn recommendation or an emailed testimonial or other declaration. If someone says you have expertise, flaunt it as Jessica says. But don't flaunt it because you think you have it.