C.,
The trick is to make sure that you are feeding her 7- 8 times in 24 hrs. at least 6 feedings in the day time so that she is getting all the calories she needs, then she will sleep longer at night. That means feeding her about every 3 hrs in the daylight hours. It is the calories that determine how long they can sleep at one time. If she gets enough in the daytime, she she will be capable of sleeping longer once you help her get out of the habit by structuring her feedings.
She doesn't need an early bed time, she cant sleep 12 hrs like a toddler so feed her and put her down for the night when you are ready to go to sleep.
To start this process, make her last nap of the day be the old 7:30 bed time. Wake her up after 2 hrs, feed her again and put her to bed when you are ready to go to bed.
So if she goes to bed when you do, say like 10pm, she will most likely wake up about 4hrs later since that is her longest stretch. again put her back in bed and let her wake you up one more time, probably around 5-6 am. feed her and put her back to bed. At this point you can let her wake on her own and start counting three hrs from when you started that feeding to get all the nursing in, OR you can choose to wake her up, lets say at 8am and start your day from there.
If you do every 2 1/2 -3 hrs, the first feeding in the "daylight" hrs would be about 8am, then 11am, 2pm, 5am, 8pm, and then 11pm, go to bed and wait till she wakes you up. start counting the 2 1/2 - 3 hours from the start of a feeding to the start of the next feeding. If it is before 2 1/2 hrs since her last feeding try to pacify her until its been at least that. By doing so you are not depriving her of nutrients, but postponing it so that she will truly be hungry and not snack. Once she is feeding with in these increments, she will eat more at one time, because she wont be snacking as often, and she will gain more weight. you will notice that once you get her feeding routine fairly consistent her sleeping will follow, and once you get her sleeping and napping consistent, she will also eat better too. They really go hand in hand.
In the DAY TIME, If it has been 2 1/2 -3 hrs, wake her up and feed her, don't let her sleep longer then that. But AT NIGHT, let her wake you up, and make sure you feed her right before you go to bed. That way you will get to sleep during her longest stretch. You can adjust the 2 1/2-3 hrs to whenever she wakes up in the morning. Just try to get those eight feedings in. Every time after you feed her in the day keep her awake for awhile like 30-60 min and then put her down for a nap whenever she starts to get fussy. She might whine or cry a little, but that is just a stress release. You will know she is not hungry cause you just fed her, and changed her so she must be tired. She should be getting 16-20 hours of sleep in 24 hrs. I know it seams counter intuitive, but the more regular sleep she gets in the day the more she will sleep at night. She should sleep 1-2 hrs in between each feeding in the day.
These are my tricks and usually by three months they are sleeping 8-10 hrs at night and taking four - five 2 hr naps a day. if you need more info, or have questions just send me a message.
Also try not swaddling her arms, she is old enough to not need the extra security. She may just be waking cause she cant move her arms.
Good luck
E.