Nicki Minaj is missing OR..............IS she Hidding Nas pregnancy?

 isn't missing, hiding or lying low because she's pregnant -- she's just been in beast mode working on making her next album a masterpiece.

Sources close to Nicki tell us ... she decided to ditch social media at the end of 2017 to fully focus on her music, which is why she's had no new posts since December 30. We're told she feels way more creative without the distractions of Instagram and Twitter.

Our sources say Minaj has been working night and day in the studio with major producers and rappers like Lil Wayne, Mack Maine and other Young Money acts ... and she's going to continue to leave social media alone until the album's complete.

Nicki's fans have expressed concern about her being MIA in 2018, which culminated Monday with Wendy Williams launching a faux campaign on her show to help find her ... replete with a missing persons poster.

But we're told all is well with Nicki -- she's happy, healthy, single and NOT pregnant, despite rumors.

As for the upcoming album ... our sources say some of the tracks are finished, and every song is going to be a hit. We're told it's expected to be released later this year ... and it's expected to be fire.