I'm having the exact same problem our babies could be twins!! Same age too. I was using SOS cos everyone swore by it and their babies are awesome. Mine wasn't working, she'd stay up for the two hours but was hard to settle, slept for 30mins, I'd get her up like the book said and wait till her feeding and sleep time which by this time she was overtired and wouldn't settle easy n sleep for 30mins again. I didn't know to look for tired signs (the book didn't say to) as a first time mum n no other advice other then to follow SOS I never knew yawning was put them straight to bed. I got in touch with another friend who went to tresillian n she gave me some advice, like if they wake after a nap don't go into them, leave them to go back to sleep (same as if u just put them to bed) I tried this, for one sleep during the day it worked for two days then yesterday was a no go, she protested till it was time to get up again. During the night she goes to bed at 7, there's always a protest tho from 15mins to over an hour!! I then dream feed her at 10:00 only to have her wake exactly 3 hrs after each feed. It's the exact same times every night on the dot. So wakes at 1:30 back to sleep at 2, wakes at 4 back to sleep at 4:30, then wakes between 6:30 n 7. I'm exhausted!! If I can getter a better sleep at night if be happy. Need to cut out the 1:30 feed but how do I know if she's hungry or just needs to be resettled? She'll always eat if I offer her boob or suck on it for comfort n go back to sleep. She too doesn't have a dummy, won't even suck on it, never has from day one. I tried only cos everyone told me to but it never worked.
I would love to know how u go and if u work things out, as ill inform u if I find a solution.
One other thing, when ur bub wakes after 30/40mins do u feed him again straight away or wait to stretch the feeds out?