Lost iPad help is needed urgently!

First: As long as your iPad had a secure passcode (known only to you and not easily guessed) your data is quite secure from even sophisticated criminals.

As far as locating it, w/o FindMy enabled, you’re unfortunately out of luck from a “technical-locating” perdpective, as that is the ONLY means provided by Apple for finding. (It sounds like you’ve already performed all the “usual” Lost and Found steps)

You might also find the info in this article helpful:

If Find My is offline or isn't working – Apple Support (AU)

Start here:

Locate a device in Find My on iPad - Apple Support

Here is Apple’s advice for lost or stolen devices:

If your iPhone, iPad or iPod touch is lost or stolen – Apple Support

Use the Find My app to locate a lost or stolen device – Apple Support

If the Find My iPad feature was enabled prior to it being “misplaced”, then if active, you would stand a good chance of locating it. 

However, if the feature was not activated prior to being misplaced - or the iPad has been inactive for more than 24 hours, the last known location will not be available - and the opportunity to use technical means to recover the iPad have been lost.

See this article as well:

If Find My iPhone or Find My iPad isn't enabled on your missing device – Apple Support (AU)