Upset at sister

So yesterday I went shopping with my sister and little girl (nearly 5 months 2 weeks) and my little one got really upset at one point and starts screaming and being hysterical. She was starving as she had last been fed at 11:15am and it was now 3pm as it had been over an hours drive to where we had gone to and we had done some other stuff first. My sister then starts saying that my girl has separation anxiety as she's just been through a phase of stranger anxiety. I had gone around to the back of the pram and she had started crying. I was trying to explain to my sister that she is just hungry and she then said how I should feed her more and give her top up bottles of formula in between feeds. She is breastfed but I'm now introducing bottles. I had to then explain how she's not hungry in general she was just hungry at that particular time as it had been so long since her last feed. Anyway we end up having some argument about separation and stranger anxiety and breastfeeding and she starts calling me defensive. I said yeah because you make me feel like I'm a rubbish parent. She said whenever she sees my daughter she's always either 'on your boob' or crying. Which isn't true at all as she only cries at nap times or when she's completely starving which is usually my fault anyway. She then starts going on about how I get her to nap as I sit in the room with her (she now goes in her cot and I feel like it's a massive achievement and I'm sooo proud of her!!) and all this other stuff. At the end I just started crying. I was so upset. Everything I do is what I think is best for my little girl. She then starts saying that she was only offering advice and that I always seem stressed out and how she's worried. I get stressed at nap times as little one hates them but apart from then we're both pretty chilled. She doesn't have kids of her own but she does has worked in a nursery so obviously thinks she knows everything! I've hardly slept last night and spent loads of time looking into stuff on the internet as I feel like I have to reassure myself. I feel like she's just knocked all my confidence. I told my husband who obviously said I was doing an amazing job. I just don't get how someone who doesn't have kids and has only seen me and my daughter a handful of times can make all these judgements (that's how it came across although she said she was trying to help). I would have thought my sister would have been a bit more supportive.

P.S. Sorry for the long post and thanks for reading! It's just playing on my mind a lot.