I feel like such a bad mom

We went to the Doctors on Tuesday and Charlotte has only gained a pound in over a month and a half. She weighs 11 lbs and 7 oz and is now 16 weeks old. She had liquid poop for the last two weeks but no fever and seemed to feel fine so I didn't take her to the Doctors thinking that it was an allergic reaction to some chicken curry I ate. It turns out that she isn't getting enough nutrients and was having starvation stool. Wow I feel like shit. I really should have took her to the Doctors sooner. She doesn't look too skinny but apparently she is. I'm having to pump often and then offer her what I pumped in a bottle in addition to our normal feedings. I also have to keep a log of when she eats, for how long or how much, her diapers, and when she throws up or spits up. If I can get her to gain weight in the next two weeks and get her poop back to normal I won't have to supplement with formula.

I feel so bad that she has had such a rough start. First it was the reflux that we fixed with me going dairy free, then the salmonella, and now shes starting to starve. We still don't know what causes her to throw up so much. We had an UGI that showed everything was fine. I'm wondering if we have another food allergy. I'm just taking it one day at a time and trying hard to stay positive.