J.L.
OK, stop stressing. I can not really help you with the breast feeding info, my son was not really into it, and since he lost a lot of weight due to his laziness, it only lasted for seven weeks.
Anyway, if you feel that you are ready and your body seems to agree, stop. You have given him three months of great nutrition and love and it is ok to stop. People will berate you for stopping saying that it is the best thing for your baby, but if it is not working for you, it is not working for him.
I look at my perfect formula fed, ultra-healthy, happy, baby and say that formula is good, and sanity is important.