My situation is slightly different as in my role as a peace officer.
I carry at least one extra magazine (16 rounds) for my Glock 32, and when I carry my 686 2 1/2" I carry at least two (2) speed loaders in left front pocket.
The vast, vast majority of time, this will suffice as I do not expect to get into a major firefight. If I was expecting a firefight, I would be carrying my AR or at least my shotgun with multiple rounds.
Herein lies the crux of the issue, as a concealed carry person, you are not expected to necessarily stay engaged other than to protect your life or the lives of your family. Total strangers is up to you, I pray you would do the right thing, but many times the right thing is to get the hell out of the area as soon as possible, and perhaps provide cover for those getting out.
It will be hard for those that have such a mindset to stay and fight but I will always recommend that your firearm should be used to provide cover fire while you disengage as soon as you possibly can.
It is a deflating idea to many to have a firearm and to primarily use to get out of the area, but remember, you are not police, you are not expected to stand and fight, and if you do and bad things happen you will be in a world of hurt.
I am expected to stand and fight and if bad things happen I may and stress may be in a better position, at least my police insurance will cover me in the case of criminal and civil process, to deal with the aftermath of shooting gone bad.
I will always recommend that anyone that carries a firearm always carry at least one reload in those rare occasions that sustained deadly force is required to resolve a situation. But the need for multiple reloads or multiple firearms places the average citizen that is armed in a precarious situation.
This is my opinion only and others should feel free to disagree to any degree they feel necessary.