My daughter is 5 and a half months old and her weight gain has consistently slowed, she only weighs 13.4 lbs. She's EBF and I feed on demand but I never let her go more than three hours during the day without eating. At night she sleeps for 8 hours and she's done that since she was about two weeks old. I'm worried about her weight gain because she was born at 9.1 lbs in the 93rd percentile and now she's in the 6th. I don't know what to do. I've thought about setting an alarm at night and waking her up to feed her after 5 hours but I'm terrified that doing that will mess up her sleeping. I've thought about supplementing with formula but I'm so against formula for personal reasons and really only want her on breast milk but I also want to do what's best for her. I just don't know what to do :(

Edit: her first pediatrician was concerned about her weight and told us that my breast milk is calorically insufficient and to wake her up at night and switch to formula. My husband got a new job so our insurance changed and her new pediatrician is not concerned about her low percentile as she's a super happy baby, has super chubby cheeks, chunky thighs, and is meeting all of her milestones.

Second edit: so for the past two days I've been supplementing 2.5oz of pumped milk in the morning and at night and in two days she's put on 4oz which puts her up to the 10th percentile and I'm feeling so encouraged! I'd like her to be back to where she was at her 4mo appointment which was the 16th percentile by the time we take her for her 6mo appointment in a couple weeks and I think if we keep this up we'll get her there. Thank you for the comments, I appreciate it. I just worry about her so much, I want her to be healthy and it's hard to feel like I'm enough when she was dropping so drastically.