Basic math doesn't seem to be your strong point. ;) It has been a bit over 13 months. 1.5 years would denote 18 months.

As for content, it made sense IronGate scaled back adding new major stuff, until major game bugs are fixed first, as well as improving overall code structure. So they are working on Mistlands biome, as well as some in-between content. More players mean more opportunity to find bugs. IronGate didn't expect millions to be sold. Which meant millions of players testing the game finding bugs.

An experience-based guess would mean it should take about 2 to 3 ish more years for version 1.0.

Also, if you read the patch news' stories, you would have found out the 28 updates they released since Early Access release wasn't about 'a new wall colour'.