Oh bedlover that's bloody hard core!!! It def sounds like you are on the right track with going up a routine. Maybe not tired enough. Has bub been on SOS for long? I found my son moved through the routines pretty quick so don't be scared to follow bubs lead and move up if you think bub is needing less sleep then the routine for his age says.
Oh and you mentioned you also have a toddler who is pushing boundaries. Do you have tizzies toddler book? It might be a big help to you too. Lots about boundaries in it.