Irritated at "adult" immaturity

I work at a preschool, and my coworkers came to me to make fun of a woman who was still breastfeeding her 16 month old who has all her teeth. First of all, my coworkers are grown women in their 50's. They work in childcare and should understand that breastfeeding is best. Second, the baby isn't even that old! One of my coworkers shuddered and said that she only nursed for 3 months and acted like it was gross to breastfeed after that. I was already having a difficult day because I have been "evicted" out of my pumping space at work and I had to pump in the bathroom all day and then I had to deal with my two ignorant coworkers. I'm still breastfeeding my 7 month old, and it makes me wonder if they think I'm gross for feeding my baby. Thank you for letting me vent. I needed to vent to people who hopefully understand my frustration.

*EDIT* the baby was 20 months. My math was off... but it's still upsetting to me!