Former breastfed babies

My daughter will be 3 in October. She was breastfed until she was 15 months old, rarely ever taking a bottle (daycare 2 days a week for around 3-4 months and a hospital stay for me that she couldn’t be there for). So mostly exclusively breastfed. I am 27+2 and the boobs are starting tondo their typical thing. We’ve explained to her that she’s getting a little sister, and sister will also get boobie milk, and all the other details you go about while explaining a baby to a toddler. Lately she’s been very clingy, but not just to me, but the boobs. She wants my milk. She wants to fiddle again, she wants her hand down my shirt at sleep time again. All the things she did while bf, she’s tried starting back up. Is this normal? And what should I do to help her adjust?