Yeah I do also think it's totally possible for dany to have gotten there fast. But that dragon death was absolutely devastating.
Well Ravens are better flyers than pigeons (as Maester Aemon points out at some point) and we have plenty of data from pigeon flying.
In long distances they fly at around an average of 50mph. Dragonstone to Eastwatch is around 1500 miles, so a pigeon would take about 30 hours for that journey (if it could go for that long). It seems reasonable to me that a raven might take less than a day, and dragons a lot less than that. Especially considering that this is Westeros, which is full of maigic. The ravens might well be fairly magical birds in terms of speeds they can fly.
Its a bit of a stretch but I think its close enough to just be acceptable. Complaints about this are pretty pointless, imo.
Yeah losing the dragon for Dany was awful, but I love the way that she took it. She now realises how big of a threat the army of the dead is. I can't wait to see how the meeting with Cersei plays out next episode, if it happens at all.