Thanks for the replies.
Well the consensus still seems to be to stretch her out further, plus try a slightly later bedtime.
The problem is, by making her go 4.30am to 8.30am I am already stretching her to the absolute max. We've had a couple of overtired meltdowns, and obviously that's not good. So I'm kind of stuck.
I did try wake-to-sleep but she woke even earlier, so I'm a bit afraid to try it again.
The events of the past 24 hours were -
Yesterday (after waking at 4.30am) she had her nap at 8.30am, napped for one hour. I was aiming to put her down for another nap at about 1pm (1.30 if poss), but seriously she was SO tired at about 11.45 (we were heading for a meltdown), that I ended up giving in and putting her to bed. She slept until 1pm, so then I put her down for a late nap at 4pm so that I could put her to bed a bit later. She went to bed at about 6.50pm.
This morning she woke at 4.10am. I was just about ready to admit myself to the local psych hospital

. But there was no way 4.10am could be classified as morning, so I just proceeded as though it was the middle of the night (resettling etc). She fussed on and off until about 4.50am, when she went into full on crying. I let her cry for a little bit, going in and out and patting etc., for about 15 minutes. Still crying. Just after 5am I tried to give her a breastfeed, but couldn't get a let down (I think both of us were just so exhausted). Put her back to bed (about 5.10am) and we both went back to sleep until about 6.10am.
So that was all pretty bad, but different from the norm. I put her down for her nap at 9.20am, which at least is a "normal" time.
Now - if any of you read this fairly soon, could you please advise as to what time you think I should put her down for her second nap, and bedtime?
Thanks so much. I do hope I can report at least a little improvement soon.
Emma