With proper routing scheme you could have a few million, and it would still cost you a few lines of code. Crawling and indexing websites is not something that is done few milliseconds after you push a new content. But you still have a very powerful tool to tell Google "hey guys, I did major change and need my website reindexed". You do this with webmaster tools. Now it's not a matter of using Google's amp. It's how your website is structured at the moment it is remembered by indexer. You could have replaced WordPress with something else and you would still face the same problem. You see, you can modify that 404 URL to cached:shkspr.mobi/... and see what the content was the last time that site was indexed. First of your problems is that you did not take care of redirecting your website. Second is that you likely have very long caching settings on each of your pages. Third is that you probably never used webmaster tools. Go check the third option. Will save you some trouble next time you do a major change.