My baby will be 4 weeks old on tues and,?

she is taking 3 oz every 3 hours. last ped visit a week ago she told me that any more than 3 oz right now would be over feeding her n try to soothe her other ways afterward if she still seems hungry, but she never told me when it was okay to give more than 3 oz. but anyways after she has 3 oz she still seems hungry and spits out her pacifier when i try that. usually she just ends up falling right asleep tho. last night was different tho,she cried constantly after she ate for almost 3 hours straight and nothing would soothe her, i tried gas drops, swing bouncer, singing, laying her on my chest, walking around with her, rocking her, swaddling, everything. nothing worked, she finally was fine when she ate again n fell right asleep afterward. i'm worried she was still hungry last night n thats why she cried? and i should be feeding her more? but the ped told me not too. so i'm so confused. my mom told me to just feed her because she knows when shes hungry but im scared to over feed her because she has a problem with spitting up as it is and got dehydrated her first week home from spitting up so much. today ive been giving her a little over 3 oz even tho i was advised not too last week and shes been fine spits up a lil after tho. i'm only 20 and i dont know very much so im just seeing if other people have any advice. thanks