Firstly, the reassurance. Your daughter has STTN since she was 8 weeks - that's amazing!! Pat yourself on the back! We didn't get STTN until DS was 8-9 months, and not consistently until he was 2! Obviously you are getting something really right for her.
So, with the thought that she is doing really well at night, it might be one of a few things:
- She is getting most of her sleep needs at night
- She needs to learn to transition between sleep cycles during the day
- It's one of those developmental things that she will grow out of in time (I think there is normally a short nap period at about this age)
My DS is low sleep needs andd whilst I followed EASY, his naps were never going to be as long as the book said (it took me a while to realise this). We ended up on more of an EASAE routine which worked fine for us.
Is she tired after the short naps, or doing OK? Does she put in a longer nap if she is out, say in the buggy or the car? I would give yourself as much of a break as possible and work around her naps, but don't feel the need to be home for all of them. You need some sanity and contact with the outside world, and she needs as relaxed a mummy as possible!