Some advice that I found on these forums regarding unwelcome comments was to treat them as genuinely curious questions (even if you know they are just trying to get you to wean). Explaining some facts about toddler nursing can make you more confident in your decision to continue in the face of social pressures.
Also, most people really don't get it because they have never heard of breastfeeding a child that isn't a "baby." You have an opportunity to educate the ignorant here! If we moms arent afraid to talk about extended nursing, we can helpto normalize it in our communities!