Try not to force feed, it will make them associate feeding = something scary overtime. Check if the teats is too fast/slow for him/her, at 9 weeks, my baby is using size 0 (Avent). Or if it doesn’t work, switch a bottle. Or maybe he/she’s just not too hungry yet. I feed on demand (she will cry for milk every 2-2.5 hours) and had no issues. If she doesn’t want anymore, I’ll just wait till she sleeps or try to feed up the rest within the next 30mins - 1 hour.