Your post could have been written by me a few months back! I followed pretty regular GF type routine with both DDs but with DS (SO hungry) I found it harder to get things organised and also found I was slipping into depression and was particularly troubled by insomnia after night feeds, which triggered a vicious circle of lack of coping due to exhaustion.
Regarding your initial question of how to get into a more settled GF type routine, I started with the naps, rather than the feeds. Start the day at 7am (if you can) and she is likely to need a nap at 9am - regardless of when you fed her during the 7am to 9am period. Wake her by 10 am and she is likely to need a nap again around midday, again, regardless of feeding. Once I got these first two naps structured (and yes, I did a lot of rocking / patting / feeding to sleep) I found that the morning feeds settled into place around them. In the afternoon we never got on with GF feeding (i.e. feed at 2.30pm then expect them to go through about 6 / 6.30pm), but we soon found our own pattern, feeding at 2 / 2.30pm after he woke from lunchtime nap, then again around 4.30, then he'd drop off for a cat nap - handy as I could give the girls tea, then we'd go to the bath time nightmare then feed again then bed (sort of following the principles of her split feed I suppose).
The reason I'd say start with the naps is that small babies' tiredness seems to be more predictable than their hunger and once the naps are in place the feeds tend to follow. DS is now 5 months and he would be in a great routine if the school run hadn't reared it's ugly head last week and completely thrown us off track... arrrgggghhhh!!!!
I will say that getting my life into a more structured pattern undoubtably helped me to beat back incipient PND.
Good luck. I'm sure the green poo will settle down - I had periods of it inexplicably on and off with all three, I think it was generally during periods when my milk supply was adjusting (growth spurts etc), I don't think you need to worry too much if her weight gain is good.