Sydney Hardeman — the viral Beyoncé fan who recently took her own life — had realized her dream of becoming a pilot … and she worried being too open about mental health struggles could doom her career, TMZ has learned.

As we reported … Sydney died by suicide on November 8 at age 25. She was engaged and set to be married this upcoming April … and had reached viral fame for her reaction to Beyoncé’s 2018 Coachella set.

Jamie, Sydney Hardeman’s mother, tells TMZ … her daughter was concerned about seeking help … because being so open about her situation might have ruined her career.

The FAA requires pilots be given routine mental evaluations a couple of times a year … and Sydney told her mother some pilots feel like they can’t be honest — because they could end up grounded. Jamie tells TMZ … she now believes Sydney was speaking of her own experience — even though she never outright said it.

We’re told Sydney wanted to undertake the initiative of making sure pilots had places to go, and people to turn to – without fear of being grounded — before it got too dark.

In the wake of her death … the family has been overwhelmed with support from the Beyhive — and were very moved by Tina Knowles’ message of love and support.

Jamie tells us the family has not heard from Beyoncé herself … but would be deeply touched if they did.