Prama i've been wondering if you are ok, we all know how hard you have been trying. When i stopped bf'ing with all my girls around 7 months i felt terribly guilty then so no matter when you stop you have some sort of guilt. If you do decide to switch the guilt does go away pretty quickly (well did for me) so just do what you think your gut is telling you. You need to weigh up how bad you feel from the pain both emotionally and physically V's the guilt of stopping. If you really want to persist then maybe you should see a councellor.
Whatever you decide you are an amazing Mum and are doing the best thing by your little boy. I still have pain when feeding especially with the letdown and the way i deal with it is to focus on something else because if i think about her sucking the feeling is so much stronger and more painful, the mind is very strong. I don't like seeing you so upset, i hope you feel better soon hun xoxoxoxox