I think that you might be suffering from too short a's in the morning which are resulting in a lack of sleep in the afternoon leading to ot at bedtime. X shows tired signs after 1h45 in the morning, and if we put him down then he gives us a 30 minute nap, but if we stretch him for another 5-10 minutes we get over an hour - so I wonder she is still stuck on her old a time and showing you sleepy signs, but would actually managed a bit longer if you pushed her a little. I know that you are still getting a good first nap, but I remember with dd2 that we would still get a good nap if ut, but it mucked up the rest of the day.
In my experience, waking 45 minutes after bedtime is always ot, and I agree with becky that a 30 minute nap between 4.30 and 7.30 would not be enough. Incidentally, our day is still 11ish hours, so x is normally in bed by 6.15, sometimes 6.30, when he wakes at 7.
As for the dummy, it might be becoming a prop, but if she is finding her thumb then you might be able to push her to get rid of it. We took the dummy away from x yesterday because our nights were getting ridiculous, and it has spurred him on to find his thumb and he went down independently without even squeaking this evening - he put his thumb in his mouth as I laid him in his crib.