on the verge of crying

Paulina
I know I'm probably way over thinking but as a mom it's really hard not to and the thought my baby girl isn't getting what she needs is killing me. 
 
I'm about to cry because Kenzie is almost always hungry. She'll nurse for over an hour and still be hungry but as soon as I give her a bottle of milk/formula when I don't have enough expressed milk she instantly isn't hungry anymore and falls asleep. She's also dropping weight and I now have an appointment to go see her pedi as shes never passed her birthweight and she's nearing four weeks old...
 
I just HATE thinking she's not getting what she needs from me some days... Some days my breasts are super full and sore and she will nurse and be completely content... And then some days like today she's not satisfied until she gets a bottle of pumped milk...
 
I wanted to EBF and up until this past week I had done so and I've finally caved and given her expressed milk... It's made me super depressed thinking I may not be able to go back to EBF and may have to start giving formula as having fat free milk runs in the family and with her dropping weight they think that may be the cause...
 
 Anywho sorry for being a big baby just needed to get that out there...