Thinking about giving up breastfeeding :(?

My son will be 6 months old on the 16th of this month and I have been exclusively breastfeeding him until about 3 weeks ago when I fi ally started supplementing about 2 times a day...I feel so selfish for this although I only planned to breastfeed for 3 weeks...I feel like if I can make it 6 months I can go a year but im so tied down and he is soo attatched to me...which I love btw but he is breastfed by demand...I cannot seem to get him on a regular feeding schedual and he is a snacker so I never know when im gonna have to nurse him which makes it very difficult to run errands ect...I also have a 4 year old daughter in school and I am very involved with the activities thy they do. I feel soo selfish bu saying that I am ready to start exclusively formula feed him but I am really starting to think that I am....I have been very attatched to nursing him and have only been away from him one tome and that was for 6 long hours....I don't feel like I need time away from my precious baby but breastfeeding a snacker at 6 months is wearing mr down I can hardly get things done around the house or anything....please tell me im not alone I feel sooo horrible