Hugs honey, its totally understandable - babies are so confusing. These early days with a new baby are hard, even without PPD, additional children to care for, etc.
So from 2:15-7:13 she may be treating it like her night like the long naps she was having at the end of the day when all this started.
I think you're right and her night has now shifted from 4-4 to 3-3 and now to 2-2. Really if you want to get her 'right' in terms of day/night, here are the steps:
* Outside in the sun for a little time during every A time if possible, most importantly the first A time of the day.
* No nap longer than 2hr during the day
* Minimal interaction during night wakings (pick your time, eg. 7pm-7am and every waking there is considered a night waking) - feed, change nappy if required, no talking, no unnecessary light.
I think re: feeding fast and frequently at night, maybe just block feed then, since your other feeds seem a reasonable space apart and the early hours of the morning are when she's struggling most. I'd also suggest lying back to feed then, as that's when your supply is highest since you've been resting your energy can go into making milk
http://www.biologicalnurturing.com/I'm happy to stick with you til we can get this sleep thing sorted out. Do you have any IRL support re: PPD? Please feel free to post on the PPD forum for advice and support relating to that if you need to. You need to look after yourself too, in all of this