Congrats. It is nice to know you are able to BF for this long.

I BF DS3 and DD for 21 months and 21 months and 9 days until they both self weaned (that was a sad day)

So feel proud and don't worry what others think. my inlaws used to make jokes and say you will still be feeding them at school. I would just laugh it off and ignore them as they were ignorant to the benefits of breastfeeding..