I don't know! I nursed DS till he was 24 months, he fully weaned the week after he turned 2. I was sad at the time, though also relieved because I was 7 months pregnant. At the time, he could barely string two words together and was still very much my "baby" in my eyes.
I am currently nursing DD who is 18 months. Sometimes when we NIP it feels odd because she acts like such a grown toddler. She's full of sass, talks in almost complete sentences, and with the exception of nursing frequently is extremely independent. At home it feels natural. Out in public I'm finding myself trying to overcome hang ups I never knew I had about people judging me. She can clearly talk and asks for milk often, accompanied by the usual toddler chest-grabbing. Since DS could neither say nor sign milk till after he weaned, I think that was my crutch. He was also extremely small for his age, off the charts even. Now I have no "excuse," and for some reason that makes me a little uncomfortable. But it doesn't change the fact that I still do it anyway, and don't have plans to wean anytime soon.