My door faces west, and there is still one missing in the northwest corner. Is this bad for feng shui? How to resolve it?

There is no good or bad feng shui. It depends on whether this pattern has a substantial impact on you and whether there is a solution. In general, the lack of northwest corner needs to be solved. Taishan stone can be used to fill corners, but it needs Feng Shui master to do it, so that it can be more spiritual. for reference only