flat feet, maybe?

Hi Everyone, Since our K began walking a few months ago, I have noticed that her feet seem flat. I have read that at this age (now 19 months old) that their arch does not yet show, and a pad of fat covers where the arch would be. BUT, to me it looks like the bone on her inner part of the foot touches the floor, her feet seem to roll inward some when she walks, then yesterday it looked like her achilies tendon on the back of the foot curves somewhat when she walks, like since the foot might not be straight. Then tonight when she was running in the house, I noticed again how she her running doesn't seem quite right, and don't know if this could be due to her feet. How do I know at this age if she could have flat feet? I do have flat feet, so maybe this is why I am looking so much at it, maybe too much? I asked the doctor last visit at 18 months, and he looked at how she walked to me, but she was wearing socks. Should I go to her doctor again, or should I look for a pediatric podiatrist, if there is one?The concern keeps coming back to me.