How to deal with question on why you are formula feeding not breastfeeding?

Hi all, Just needing to share and get any advice. I had issues with feeding my little one. Due to not having enough milk and then stress reducing it even more and her struggling to latch. Resulting in her loosing a lot of weight. This resulted in us having to use formula. It took along time for me to accept this (I have now, my beautiful girls 5months now and thriving ) However my sister has now had a baby and is asking me all sorts of questions about feeding and sharing her experience (she’s a big sharer) and it’s really bringing back all the bad memories and moments we had.