Range of a small revolver, +P loads, Shooting Someone, Mindset, and the Aftermath.
If you look at the different ranges that people are in when they communicate with each other you see the distance that people are at when they are close, when they are friends, when they are business relationships. How a far away before you use your weapon. I need probably 6 feet or greater but I much prefer 15 feet.
The things that people forget the closer the person is the greater the amount of area he provides as a target. Photographers know this rule very well. The closer they are to the subject the less area they can get in the frame. In other words if you are photographing a person the closer you get the more of the frame the person would take up.
If you think a J frame is too small to be accurate with take a target with a silhouette on it and put it at 5 feet, then 10 feet, then 15 feet, and then 20 feet. You will see the closer the target is the easier it is to hit even with a J frame. I saw someone talking about 25 yards which is 75 feet. 20 feet is a little less than 4X the distance or it is about 1/4 the distance. A 4" gun is going to be accurate and have less kick but at close distances a 1 1/2" revolver should do fine. I wouldn't use a +P load because the small gun with have a larger kick, which can affect your accuracy, and the ability to fire off another round. Also the +P make a small revolver harder to hold. Small guns don't tolerate the +P loads very well for extended periods.
There are some companies known to make self defense loads and the ones I have tried aren't +P and I have seen they are more accurate with less kick.
All this being said do yourself a favor and take a self defense class. The strongest method of self defense isn't a weapon but it is being aware of your surroundings, avoiding isolated areas, and don't be in areas considered unsafe. As I have said before if you are jumped being unaware of your surroundings having a weapon isn't going to do you much good if you can't use it to defend yourself. A gun for a woman is a good equalizer. Here is the thing to remember if you ever have to use it for self defense and that is: it is him or you and there is no second place. The person that walks away alive wins. Your intent if you have to defend your life is you've got to do what is necessary, if your life or somebody else's life is threatened, and you do this until the person is no longer a threat and then go no further. Remember it is him or you.
In the end you are much better avoiding an attacker than having to fire upon one. If you ever shoot someone there is a huge bunch of red tape attached to it. Usually they will need your statement, they may take your gun, you will be interviewed by police, then you will be investigated by the police for a certain period of time, if they find it isn't self defense you could be tried for assault or murder, and if you are tried and acquitted the victim him or her could sue you and if they die then the relatives can sue you. The evidence they need to prove excessive force is easier to prove than murder. I haven't talked about having witnesses, talking to the police, securing evidence to prove your story, remember what happens so you can recount your story, needing counseling for post traumatic stress, psychologically you could have memories of the event reoccur, anybody being shot on TV can be traumatic, and you can question yourself whether you did the right thing.
Shooting a person is a huge thing. It also involves a legal issue of what you can and can't do and whether the shooting is justified so it can be called self defense. It is always better to avoid the situation if you can at all possible but if you are in danger of being injured and/or killed or someone you know or a relative than you have to take action. I see people talk about have a CCW as protection but in the end if you can possibly avoid using it you are better off. Walking away is so much easier. To get a inkling of what post traumatic stress can do it is a good idea to look it up. You probably will be a changed person after you shoot someone. Remember this isn't TV.