Dropping a day feed?

Lately (like the past week) my formula fed baby has been seeming more and more disinterested in eating at some of her feedings every day. She will just laugh and play and look around and just doesn’t care about her bottle haha it’s like I will have to force her to eat 3 ounces and then the next feed she will eat 5 or 6 and then three hours later will only want 3 ounces and will be completely distracted. Today I told the lady who keeps our baby to just feed her when she gets hungry and see what happens. Well, she ate four hours apart both times and ate 5-6 ounces both times. We still tried to get in her two other feedings tonight before bed but she still only ate 3.5 and 2 ounces before she passed out after eating because we had kept her up later to feed her. She does sleep through the night (12 hours) since 8 weeks.

Sorry this turned out to be so long, I just don’t know what to do?? I feel like four feedings isn’t enough, but I guess she’d be getting the same amount just less often? She’s still getting lots of wet diapers. I am just so confused 🤷🏼‍♀️🙈

ETA: she is 13.5 weeks old

ETA2: right now she eats(or she did before this week):

6:30am 7-8 oz

9:30am 3.5-4 oz

12:30pm 4 oz

3:30pm 4 oz

6:30pm 4-5 oz