Hi L.,
This was my exact situation - I soooo feel for you! First, I will tell you to hang in there, you are stronger than you know. Secondly, I will tell you that there are moments you feel you cannot handle the crying anymore, AT ALL!!! At this point I suggest putting your baby in a bouncy seat on the floor in your bathroom, or somewhere safe where you can't hear her screaming in your ear and let her stay there away from you for five minutes, or ten minutes just so you can breathe. It's not mean, it's just to get your sanity back. Trust me, the baby at four months won't remember it and it will help you keep your wits about you.
I had a two year old daughter who was an angel, never fussy, a wonderful baby... then along came baby brother. He was colicky from exactly the time he was one month old. Every time I tried to feed him he arched his back, screaming crying. I could never get him to eat except at night when he would eat sleeping all night long, while I breastfed him. Then finally at four months I couldn't stay awake all night long and made him sleep in his crib by himself. He didn't hardly eat after that because it was so painful for him - went from 70% in weight to 20%. GI doc wanted to scope him but I wouldn't let them do it. I tried every type of formula and nothing, even nutramigen, worked. I ended up breastfeeding him until he was 15 months old. His "colic" got better at around seven months and he started to eat while not asleep when he was around six months old.
I know that it seems sooooo hard right now but you will get through it, I promise. My son was on prevacid, zantac, baby gripe water, probiotics, we even went to a chiropractor - everything a baby could try and NOTHING worked. I think he just had a very sensitive stomach, colicky and hurt all day, every day. Sounds like what you might be going thru. I wish I had some wonderful answers but unfortunately for me I never found anything that really worked - my son just finally "grew out" of it. He will be four years old next month, and he is still a very picky eater, but he's gone up to the 50% for weight and he's a happy, playful, rough and tumble boy, perfectly normal. If you really are concerned, you might try a GI doc at Children's Mercy, although it will take around four months to get in probably and they will if anything want to scope him so if you're ready for that, then that's the next step you might try...
best of luck to you - I wish I had more suggestions but at least you know there are others just like you in your same spot who have been there and I promise you, you are not over reacting, you are not an uptight mom, you just have a very difficult baby and my heart goes out to you. God bless you and hang in there!!!!