Funny you say that!!! I was watchng the Vannessa show earlier and it was about working mums and going back to work etc. They were talking about how lots of mums who have pressurised, high powered jobs etc etc all of a sudden once they have a baby lose confidence and really start to doubt themselves as a mum.. Exactly like what you have said!!
Firstly, remember you know Erin best, you are her mum it is down to you and OH to be confident and make decisions about her life, you are doing great and she's happy so now to the next step.
So you know you need to really wean in the next 4 weeks, so why not set a date? Day in 2 weeks time, get everything ready, read up on it so you are confident about it all, maybe prepare some foods so in your mind you know exactly what you are doing instead of going in blind??
Annabel Karmel does a good shedule/meal planner that you could use as a guide so you know where you are going with it?