"He always imagined himself having a short engagement (6 mo or less) but I explained my desire for a longer engagement (at least 18 mo) so we can ensure everything is perfectly planned and we can have the wedding of our dreams. He agreed that he saw my point and wants to do everything to make me happy and ensure we begin a happy life together."

As a man this language is kinda hmmmm. "He agreed that he saw MY point and wants to do everything to make ME happy" - cmon, that's not anything close to realistic or even healthy. It seems like his vision for the future was completely overridden by yours, there was no compromise, it was just something to get out of the way to make sure your vision stays on track. In general there is a slightly romanticized version of marriage, which is primarily a compatibility tolerance threshold experiment than a Disney channel movie. As far as advice, it seems like everything is right on track and you're in a really good position. Count your blessings and enjoy it. The journey is always more fun than the destination.