Hi DaniellaBella,
Have you tried a HugABub style wrap? Bubs is in an upright position in there. It was the only thing that worked for me in the first 3 months. And I used it a lot for another 4 months or so. An absolute lifesaver. You might be able to try one a friend has or pick one up second hand. Or even make one yourself (quite a cheap way to go, depending on the fabric you chose).
Rest assured, your bub will sleep when she needs it.
Or have you tried "driving" her to sleep. Although my DD hated the car, I've heard of lots of people driving the kids around to put them to sleep. not exactly an environmentally friendly or cheap option (with current fuel prices), but it might save your sanity.
At about 6 weeks I just completely gave up on the cot (until I gave it another go at 6 months) and just co-slept. During the day, if I didn't have the luxury of time to have a nap with her, I would feed her to sleep on my bed and then sneak away once she was asleep. Same in the evening. When she started rolling, I put a bedrail on my bed.

Hope things get better and you get some rest (and well-deserved me-time).

Sasa