I'm trying to wean my 3 year old.

I really feel you on this, weaning a toddler is so much harder than people make it sound, especially when they are emotionally attached to nursing. What helped us was gradually shortening the sessions first rather than stopping cold, and I also distracted my girl with a special snack or activity during the times she usually asked to nurse. Give yourself grace lah, it is a big transition for her and it takes time, so just go at a pace that works for both of you.