I've been thinking about this more than I should. Is the .38 enough? It depends what enough means. The vast majority of law abiding civilian individuals will not actually use a firearm in their lifetime. Someone noted above, and I will accept it as true, that most uses of a firearm in self defense will involve less than three shots.
Enough for what? Its not about being enough to overcome any possible attack on your person or those you are willing to protect with deadly force. Face it we cannot do that and our best chances of overcoming an attack involve a long gun and if were discussing long guns no doubt someone would point out travelling in a Bradley combat vehicle would be within reason.
I am not a "carry a gun everywhere I go every time" though I do tend to carry a gun virtually everywhere I take my children. As noted above retreat can rapidly become less of a viable option when others are involved.
Few of us are ever going to actually need that firearm for self defense. Fewer still will need to fire a shot as the show of the firearm will end the threat or make retreat possible. Even fewer will need to fire more than one, two, three... well you get the idea. The people who will need more than 5 shots in a gun fight? An extremely rare group. Its made even rarer when you consider "need more than five but less than X" with X being the amount of rounds they actually carry.
But back to the question: enough for what? I believe we actually carry are guns for comfort. It is highly likely I am never going to use my gun and yet I go through the trouble of carrying it many places. When I take my kids hiking or to the playgrounds I carry a firearm because it gives me a level of protection that I feel more comfortable with than if i was unarmed.
So if carrying a gun is really about making you feel comfortable with the level of protection you have for yourself and those you would defend the question becomes far less empirical. It changes from being quantitative in nature (will X shots be enough) to being qualitative (am I comfortable enough with this gun) and becomes, even more than it was, a personal decision.
Is the J frame enough? If you answered yes to the question than it is. If you really had to think about it, wonder, and it still nags at you? Nope.