Well, I can relate to some of your prblems. My dd is so erratic with everything, it is a miracle we managed to have some sort of a schedule at all. She would fall into some sort of predictable routine, and then in 2 weeks time all was gone and we had to start from the scratch. She was waking often at night, sometimes 2 times, sometimes 4 times, sometimes hungry, sometimes couldn't go back to sleep. Then, she would be up at 6 am, next day at 8 am. And it is like that even now, minus night wakings, she happens still to wake up once from time to time.
Today, she woke up at 6 am and I knew she would not last till her usual nap time and of course she fell asleep in the car! So yes, things are unpredictable here and she is 18 months.
I think that we tend to think that bottle would make it easier for us but I was always wondering if those middle of the night nursings aren't actually easier when you breastfeed compared to preparing bottles, mixing them and so on, while your baby is angrily screaming for you to rush LOL. At least my dd was angry when I was not feeding her right away.
Just my thougths...