If I can throw the brakes on here for a second... So you're riding a bike that you're generally happy with, right? I mean, it sounds like you could maybe raise the bars a little (which is really easy to do), but you're not experiencing any pain or discomfort? Everything is basically ok so far? If that's right...go ride the sucker.

The people advising you that your bike is too small...well, they may be right. But bike fitting seems to me to be the sort of thing that requires more than just your height, inseam, and bike size -- you generally want to lay eyes on the person, as I understand it. And it sounds like at least a couple of bike shops have now done so, and have told you that you should be riding a pretty small bike. Since you're already riding a pretty small bike, you may already have what you need.

So if I were you, I'd take the bike to a reputable shop and ask them for a basic fitting. They'll typically charge for that, but it's worth it -- and most shops will do a basic fit for not too much money. They'll raise your bars for you, get your seat where it should be, and probably give you some good advice on shoes and pedals. And if instead they get you on the bike and say "holy smokes, this bike is way too small for you," then you know. Otherwise, you'll have the peace of mind to know that you're on the right bike, and can ride out happy.