My mom bf'd our older sister for about a year (?) which was the "advice back then" and breastfed my twin sister and I, against nurses' advice (they said it is "impossible to nurse twins"- ha!) for about 9 months until we "weaned ourselves". I'm pretty sure nobody weans themselves before 1 year, but I'm sure I am proud that she bucked the odds and breastfed us at all. She seems a little embarrassed about believing the advice she was given as far as when to wean, and feeding us on schedules (she is proud of "cheating the schedule"- they doctor told her to feed us every 4 hours but she fed us every 3), but also seems a bit weirded out by full term breastfeeding (my twin's son is 3.5 and mine 3, and our big sis nursed her girls past 2 yo). She doesn't back all our AP, natural-family stuff and will sneak our kids sugar when we're not around, and stick them in front of a TV. She says, in Grandma's house it's Grandma's rules" and if we want to leave our kids with her we accept her rules. And I guess we do.
Even though we were breastfed, we still parent differently and sometimes our parents take it personally as an affront to them.
Possibly your mom has felt wronged by all the "breast-is-best" adverts and is feeling defensive. I guess I would try to let her know that you understand her choices were made in a different time by a different her and that is ok. It must be hard to see you make different choices, esp if she already feels judged by the messaging.