Argh - sleep!! I felt so incompetent when #1 never slept through, infact she is 3.5 and still struggles to have a good nights sleep. #2 (who is 1 on Sat) has just started sleeping well - she may get up anywhere from 4 - 6am. To help counteract the sleep deprivation we cosleep with whomever wakes up and won't resettle. It is just easier for us - but we also are all in bed before9.30 to grab a few hours befor any party starts. It is hard to do but necessary here.
It sounds like you are doing a great job - trust your instincts and so what suits you best. I have heard all sorts of wild tales of 3 mo's being given farex/formula to get bubs to sleep through - in my experience they sleep when they are ready!!!
Hang in there - nap when you can and most of all be kind to yourself. xxx