Since you have some regular "old fashioned" moves, I recommend adding Judo. Learn breakfalls, some basic takedowns and some ways of "stopping" an opponent like chokes or basic joint locks. The key is to harness the raw principals which is to keep yourself safe (minimize danger), use minimal energy (you'd be surprised how easy it is to blow your load only to get overpowered after) and "stop" (disable) your opponent as quickly as possible. The longer you are in a fight, the longer you are in mortal danger. If you're dealing with drunk or stoned people, or hobos (people that are "dirty" or can give you a disease if touching them) you might instead want to get a sidearm. You can stop someone without causing too much permanent damage and don't have to come close. Don't fall for any of these tasers or knives as defense, as many say they end up with them being used against them. That said, find a 1-day knife fighting seminar to learn to handle yourself if someone pulls a knife on you. This way, if you take someones knife away you can use the knife without cutting yourself up. Regarding not being able to bring yourself to "hurt" them, consider again the longer you're in the fight the longer you and they are in mortal danger. Stop it as quickly as possible and KO'ing someone or ripping their knee out (14lb of pressure sideways is all it takes) will also stop them from having to take more damage from you. In other words, be in it to totally win in the quickest and most terrifying fashion, or you'll fashion yourself as a victim.