Baby hard to get to sleep -- please help!!!

Jenny
Baby is 6 weeks old and for the past 4 weeks we have been having an extremely hard time getting her to fall asleep. We discovered that if we bounce her on an exercise ball, she stays calm until she falls asleep, but it takes 30-90 minutes for that to happen. At this point, she's only supposed to be awake for a little over an only total so sometimes she is awake for over two hours before she falls asleep. We tried rocking her and a swing. 
She is not really fussy, just stares around. Sometimes she will fall asleep for a few minutes, then is wide awake again. 
We have her in a dark room, we swaddle, white noise, she sucks on a finger because she won't take a pacifier yet. 
We try to watch for cues that she is getting tired. Usually she yawns, stares into space, starts getting kicky, and then finally starts getting fussy. We have tried putting her down when she first starts yawning and when she gets fussy and everywhere in between and it doesn't seem to matter. 
Any advice or does anyone else have this happen? My husband and i are hurting from bouncing so much and are desperate.