, First of all, I would like to tell you that your concern about your web pages not getting cached is really very true and almost all the webmasters are facing this problem.
I am also facing this problem and unfortunately no buddy knows why Google is doing this, but be assured that you are not alone, we are also suffering from this issue and so far i have came across a temporary solution i.e if you are are from USA, then you can cache your important web pages manually via Google Webmaster and in case if you are not from USA then you can use VPN and do the same to get your pages indexed in Google .
In my case, we have noticed that Google is taking about 2 -3 months to cache a web pages. We have a blog https://magzinly.com/
powered by WordPress and when ever we post something new in the blog, it get indexed within hours. I think it is because of Sitemap and RSS Feeds which we have already submitted in Google Webmaster. As far as I know WordPress has builtin Ping system through which it pings popular search engines such as Google whenever a new article is posted.
I highly recommend you to create a Sitemap or RSS Feed of your website and submit it in Google Webmaster. Make sure your Sitemap or RSS Feed is dynamic in nature and updates automatically with new contents.
I have googled a lot about this issue but I was unable to find any solid information / solution about it. I think there is no one who exactly knows that what the hell is going on.