WordPress Vbulletin Google SEO Problem Need Help!

Hello WordPress.com experts,

Half year ago I started a wordpress blog together with vbulletin. I combine these two together through https://www.mywebsites.com/forums. So https://www.mywebsites.com is my wordpress blog and https://www.mywebsite.com/forums is my vbulletin blog. Now here’s the problem:

My wordpress blog generates over 150.000 visitors, the articles are indexed by Google. HOWEVER, my vbulletin forum is not moving!!! So I checked the index:

Google nearly index my vbulletin site. And I am like ‘What’s going on?’
P.S. I have bought the VBSEO too, so the permalinks is not the problem.

Now I am wondering, was it better to add my forum like this:
forums.mywebsites.com instead of https://www.mywebsites.com/forums? Is there anything to do with it? Because forums.mywebsites.com, is a subdomain, while /forums is not.
Please help, anyone who is an expert and have high traffic website with a vbulletin forum, what do you do?!!!

p.s. https://www.mywebsites.com does not exist, but it’s used as an example. I am not giving my real domain here. thanks for understanding.

p.s.s. in case you think it’s my robot.txt, this is what I have blocked:
Disallow: /forums/member.php
Disallow: /forums/ajax.php
Disallow: /forums/calendar.php
Disallow: /forums/memberlist.php
Disallow: /forums/calendar.php
Disallow: /forums/search.php
Disallow: /forums/reputation.php
Disallow: /forums/showgroups.php
Disallow: /forums/subscription.php
Disallow: /forums/private.php
Disallow: /forums/moderator.php
Disallow: /forums/profile.php
Disallow: /forums/memberlist.php
Straight from the webmaster tools.
[Duplicate. Continue with https://www.ads-software.com/support/topic/wordpress-vbulletin-google-seo-problem-need-serious-help?replies=3%5D