Rachel, Vicku is right, consistency, consistency, consistency. Just stick with the 6/6.30pm bedtimes, preferably closer to 6pm at present and she will come through this again. Its just sods law really. She does take a long time to get back on track which is mainly why you had so many problems getting her routine sorted before your holiday, but since you have had a nasty cold, the clocks changing... so its no suprise its taking a while for her to get back on track. Are you still staying in with her in am for ew's. AP definitly has its +'s sometimes, that I know very well having done APOP loads of times, but at some point you will have to bite the bullet and return to wi/wo for ews otherwise she will continue to wake just to see you and have you there for last hour or so of night sleep.
I totally agree with vicku again about the fact that at this age you can start to just go and say to them 'its still night time, you need to go back to sleep' and they do understand.
Stick with it Rachel, she's acheived a good routine before several times before, albeit for only short spells, but we know it can be done. You will get her back on track again.