Octave D unnaturally too sharp

so I played alto in marching band (school owned Yamaha) and am now practicing on my own saxophone (never played for ensemble, off Facebook marketplace, not sure brand but has same design engraving as school Yamaha). my current tuning has G (concert Bb) at least 20 cents flat. My octave D (concert F) is coming in at a 28 cent flat D# (concert F#). Any advice? I'm already used to pulling the note down to get it in tune, but I can't pull it down a half step each time it's played. Octave Eb is a tad sharp but not at bad, E is fine, it's just D that's causing issues.