Hi J.,
My son is 11 weeks, but we just went through this from about 6 to 8 weeks. It's like he just did not want to sleep. He would stay awake all day and sometimes would only sleep for about 4 hours a night, then stay awake all day again. When I tried to put him down for a nap or bedtime, he would scream like someone was killing him.
A friend of mine let me borrow a book called "The Happiest Baby on The Block". I read this and used some of the ideas in it. Also, you may just have a high-temperment baby...just like mine. :-) He did this for about 2 to 3 weeks. I was sure that he was destined to do this forever...it was making me crazy! But she will grow out of it.
Like I said, my son is 11 weeks old today, but when he was about 8 weeks old, I started doing a routine at night. I would give him a bath, take him into his nursery, dim the lights and rock him as I give him his bottle (I also breastfeed and give formula at night). After his bottle, I will sing and rock him until he is pretty good and asleep. Then I lay him in his crib and turn a fan and the mommy womb sounds bear on for noise. Sometimes his mobile with music if he's not quite asleep. He still fought me and screamed for a good 2.5 weeks.
I had to do this routine for almost 3 weeks before he started to get the hang of it. Last night was a milestone for us. I bathed him, rocked/gave him his bottle, laid him in his crib drowsy, turned his mobile on and went to sleep by himself.
My point being, it is a phase and she will slowly grow out of it with a little help from you in the way of predictability and soothing. We also tried Gripe Water (2 doses, 30 mins apart before bed) but it didn't seem to do a whole lot.
As far as formulas go, I supplemented my son with Enfamil Lipil, then went to Enfamil Lipil GentleEase, then went to Nestle GoodStart Supreme (the new kind in the green can). As far as tummy soothing and less gas, I love the GoodStart Supreme!
I hope any of this helps. Good luck!