M.R.
Don't worry about it yet. You did the right thing by making an appointment with the pediatrician.
Now, I'm not saying this is the case in your situation, but you would be surprised at how many people are in absolute denial when it comes to their child's health and weight. They have a hard time being objective and what looks like a cute tummy to them is really a potential risk factor for disease.
Bring all your questions to the pediatrician next week. And, have an open mind. No one is trying to judge or blame you for anything. If there is not a problem then no big deal but if there are early warning signs for risk of type-2 diabetes, wouldn't you rather know now and be able to do something about it as opposed to it getting so out of hand that major medical interventions must be taken?
Good luck and best wishes.