So is she waking at 6am now? And is the routine you describe what she is doing now i.e. since the clock change, or is it what she was doing before? I just want to be 100% sure on the timings. So can you confirm that since the clocks changed, her day is now like this:
Wake: 6am??
Nap: 9 - 9.30 (assume this moved later with the clocks changing)
Nap: 12-12.30 (has this nap stayed at 12pm?)
Nap: 2.30/3 - 3/3.30 (is this nap still at this time?)
BT: 7-7.30
Are you waking her from her naps after 30mins or is she waking herself?
And when you say you are trying keeping her up half an hour later is this before a specific nap, all naps or before bedtime?
If her current routine IS now as I've posted above, then I would say she is overtired. For us, 30min naps were always a sign of overtiredness. And 1.5hrs daytime sleep is definitely too little for her age.
Her day is pretty long & she is awake for an awfully long time between her 3rd nap of the day & bedtime, which won't help the overtired situation. At her age she should really have dropped the 3rd nap & be taking just 2 naps a day, however I understand the need for the 3rd nap whilst her naps are all are short!
IIWM I would probably try & do an early bedtime for a few days of 6-6.30pm latest & you might actually find she wakes at the usual time (6am) or even later. As she becomes better rested you can start to push her morning nap out a little bit towards 9.15-9.30am. Hopefully if she is better rested she will sleep for a bit longer, perhaps 45mins. Then you can push her lunchtime nap a little later to 12.30 & see how she sleeps. Ideally you want a 2hr nap here, & if you can get this then you can do away with the 3rd nap & gradually push her bedtime back out.
Might have some more suggestions if you can answer my Q's!